Add 'nodetool statusgossip'

Patch by Jan Karlsson, reviewed by Brandon Williams for CASSANDRA-8125
Fix repeated message when there are no hints to compact

Patch by carlyeks, reviwed by brandonwilliams for CASSANDRA-8247
Fix deletion for indexes on primary key columns

patch by slebresne; reviewed by thobbs for CASSANDRA-8206
Ninja: update unit tests for CASSANDRA-8206
modify test after CASSANDRA-7463 change
Add column update delta histogram

Patch by Sankalp Kohli, review by jmckenzie for CASSANDRA-7979
Fix non-text comparator col names in cql3 queries

Patch by Tyler Hobbs; reviewed by Aleksey Yeschenko for CASSANDRA-8178
Make CFMetaData.memtableFlushPeriod volatile
Remove some dead thrift code
Abort liveRatio calculation if the memtable is flushed
patch by Oleg Anastasyev; reviewed by jbellis for CASSANDRA-8164
Improve PropertyFileSnitch log formatting

Patch by Liang Xie; reviewed by Tyler Hobbs for CASSANDRA-8183
Avoid overlap in L1 when L0 contains many non-overlapping sstables

Patch by marcuse; reviewed by yukim for CASSANDRA-8211