RESTHttpsServer: lower log level on socket shutdown to warning, as an error code does not necessarily indicate a problem

Move CXXFLAGS definitions to config.mk and thus streamline compiler flags for all Makefiles in subdirectories

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

- Fixing a bug that caused endianness detection to not work properly
after switching to the new BOOST macros, causing dcdbquery and other
tools to break

- Analytics plugins can be now loaded and unloaded dynamically
- DCDBPusher now looks into the current configuration directory if no
path is supplied when loading/reloading a plugin

- Added a catch for an exception thrown when using on-demand analyzers
- Checking that the HTTPS server is actually running before stopping it in
the destructor

dcdbpusher: New PluginManager class to bundle all plugin related operations. Integration outstanding

Common rest server

See merge request !3

CollectAgent should be switched to new Rest API design as soon as possible
Minor improvements to README, Makefile and PUT /analytics/reload methods