Optimize reconnection to remote JMX agent

Merge pull request #440 from tulumvinh/2.x

Optimize reconnection to remote JMX agent

Remove backward incompatible yml files due to no support in C* 2.1 or higher

Remove these out of yml files due to no support in C* 2.1 or higher

in_memory_compaction_limit_in_mb
memtable_total_space_in_mb
multithreaded_compaction

v3.0.2

Remove 2.x build status