Increase bloom filter true positive count on key cache hit

Patch by marcuse; reviewed by thobbs for CASSANDRA-8525
Merge branch 'cassandra-2.0' into cassandra-2.1

Conflicts:
	CHANGES.txt
	test/unit/org/apache/cassandra/io/sstable/SSTableReaderTest.java
Merge branch 'cassandra-2.1' into trunk