Bump Cassandra and improve MD5 heuristic.

Makefile

@@ -4,7 +4,7 @@ include config.mk
 LIBRARIES = DCDBLib
 PROJECTS = FilePusher SysFsPusher CollectAgent ParastationProvider IPMIPusher MontBlancPusher SNMPPusher DCDBTools DCDBBenchmark scripts webgui
 
-CASSANDRA_VERSION = 2.2.5
+CASSANDRA_VERSION = 2.2.6
 MOSQUITTO_VERSION = 1.3.5
 BOOST_VERSION     = 1.57.0
 SNMP_VERSION      = 5.7.3
@@ -32,7 +32,7 @@ DISTFILES =	apache-cassandra-$(CASSANDRA_VERSION).tar.gz;http://archive.apache.o
 DISTFILES_HASHES = apache-cassandra-2.2.5.tar.gz;c3952585a03f15490da6b14f4f4a2087;mosquitto-1.3.5.tar.gz;55094ad4dc7c7985377f43d4fc3d09da;OpenIPMI-2.0.21.tar.gz;dc0b42ae40b3f1d0db2a94b75b95fae1;boost_1_57_0.tar.gz;25f9a8ac28beeb5ab84aa98510305299;net-snmp-5.7.3.zip;9f682bd70c717efdd9f15b686d07baee;openssl-1.0.1t.tar.gz;9837746fcf8a6727d46d22ca35953da1;cpp-driver-2.0.1.tar.gz;70bf83e1cbd0d35b7e5ed66fc4dccbb1;libuv-v0.10.36.tar.gz;8eb77b4fee4f311c114a9fee06f5a2ab;httpd-2.4.18.tar.gz;2f90ce3426541817e0dfd01cae086b60;apr-util-1.5.4.tar.gz;866825c04da827c6e5f53daff5569f42;apr-1.5.2.tar.gz;98492e965963f852ab29f9e61b2ad700;
 
 FETCH = wget -c --no-check-certificate -O -
-MD5 = $(if $(shell which md5),md5,$(if $(shell md5sum --tag Makefile),md5sum --tag,openssl md5 <))
+MD5 = $(if $(shell which md5),md5,$(if $(shell md5sum --tag Makefile 2&> /dev/null || true),md5sum --tag,openssl md5 <))
 
 MAKETHREADS ?= $(if $(findstring $(shell uname),Darwin),$(shell sysctl machdep.cpu.thread_count | cut -b 27-),\
 		$(if $(findstring $(shell uname),Linux),$(shell cat /proc/cpuinfo | grep processor | wc -l),4))