Remove  maxConnPerHost and maxConcRequests configuration parameters in Collect Agent as they have been deprecated in Cassandra

- Fixed name of log files for collectagent
- Fixed a few compilation warnings under gcc 7
- README for dcdbpusher now correctly refers to dcdbpusher.conf files
- SensorNavigator is rebuilt after plugin reloads only if data analytics
are currently running

- a "filter" configuration parameter has been added, which is used
to discard sensor names when building the sensor navigator
- Can be used to e.g. build a sensor navigator in a collectagent
using only the sensors that are directly collected by it
- Implemented a switch to select leftmost/rightmost binary search
in CacheEntry, used for the QueryEngine

- Parsing of host:port network addresses is handled by GlobalConfiguration
- -p dcdbpusher command line parameter (broker port) removed and integrated
into the -b argument

- The GlobalConfiguration class includes all shared logic to read and
parse configuration attributes for the collectagent and dcdbpusher
- The class is further expanded to add application-specific
configuration parameters and blocks

- When performing sensor queries with absolute timestamps (rel=false) a
binary search algorithm is used to compute the bounds of the required
sensor cache view
- This is more accurate than the fuzzy method employed with relative
timestamps (rel=true)

- The REST API of the data analytics framework is now functional in
the collectagent as well
- This implementation is temporary and should be replaced with a generic
REST API server whenever possible

- Batch size in the collectagent now taken into account to determine if
a specific sensor cache is stale or not

- Integration of data analytics framework in collectagent complete
- REST API integration still pending
- Added some documentation to the code

- QueryEngine integration done (but not functional yet, debugging required)
- Changed behavior on exceptional conditions: if SensorNavigator or
AnalyticsManager initialization fails, termination follows
- Now the QueryEngine can also access output sensors of other Analyzers
- Minor bugfixes

- First step for integration of the analytics framework in the collectagent
- QueryEngine and REST API integration still missing
- Proper testing still to be done
- Added a probe function: the global config file is scanned before
initialization, and if no data analytics plugins are requested, no
sensor navigator is built

- Boolean configuration options now all accept "true" and "on" keywords
- Cache interval and thread count parameters removed from the command-line
interface for consistency; these can still be set in the config files
like all other parameters
- global.conf file renamed to dcdbpusher.conf for consistency

- Sensor caches across DCDB are now managed by the CacheEntry
implementation under "common"
- Provides utility methods to perform averages, checks, get views etc.
- SensorCache class in collectagent kept due to its libdcdb dependencies

- Added a 'common' directory where all shared code has been placed
- Analytics package has been moved out of dcdbpusher, now has its own makefile
- Some renaming here and there for uniformity

- Fixed a minor issue that caused text corruption when using the -h
option on certain shells
- Collectagent now exits gracefully also when receiving a SIGTERM signal

- Added configuration options to tune the Cassandra driver for
optimal performance
- Added a "debugLog" configuration switch that enables logging of
errors in asynchronous inserts in the Cassandra driver

- The CollectAgent sensor cache is automatically purged each X seconds
(X is configurable through the cleaningInterval parameter), deleting
all entries than have not been updated in the last X seconds
- Fixed some minor bugs related to index management in sensor caches

- Round-robin thread-to-connection assignment policy (speedup on
small instantiations)
- Sensor cache entries are pre-allocated to avoid reallocations, and
shrunk to the correct size later
- Avoiding heap allocations during message processing and recycling buffers

- Added BOOST logging in the style of dcdbpusher
- All logging-related functionality is in logging.h

- The collectagent is now configurable, like dcdbpusher
- Available config options can be seen in the sample collectagent.conf file
- Supplying a path containing config files is mandatory, like dcdbpusher;
this may change in the future
- Please do a make all && make install from the root of the repo to update
scripts and directories that were modified to add config support

- MQTT publish messages that have a topic preceded by the /DCDB_MAP/
keyword will be interpreted as sensor name auto-publish messages
- The payload of such messages is a string defining a sensor name, that
is used together with the MQTT topic to perform a "sensor publish"
action on the Cassandra db, like dcdbconfig does

Beautify usage output, streamline parameters with other DCDB tools, and use more meaningful parameter characters