Reverting maven-surefire from 2.16 to 2.15

2.16 included a regression that makes it impossible to run a single
test method.  It's still possible to run all methods in a single class,
just not a specific method.

 http://jira.codehaus.org/browse/SUREFIRE-1028

According to the 2.16 changelog in JIRA, the only substantial changes
vs 2.15 were new parallel test execution options, none of which we
actually use right now.  I do use single-method test execution though.

 http://jira.codehaus.org/browse/SUREFIRE/fixforversion/19331
Make BytesToken format hack safe on other tokens

Check that objects of general type Token<?> pass an instanceof
BytesToken check before trying to apply a hack for
https://issues.apache.org/jira/browse/CASSANDRA-5566

I think it was impossible for the hack to have fired prior to this
commit.  It was guarded by a regex on Token strings that looked for
"Token(bytes[.+])".  Murmur3- and RandomPartitioner return LongToken
and BigIntegerToken, respectively, whose toString() methods both
return strings containing only decimal digits and a minus sign.

Still, I think the check is useful in case somebody has a third-party
partitioner that uses tokens returning arbitrary strings.
Add Cass storemgr method to get IPartitioner
Rewrite getKeys methods in CassandraThrift

Also added new getKeys test methods to AbstractCassandraKCVSTest and
KCVSTest
Commit cleanup in AbstractCassandraKCVSTest
Import, warning, and loglevel cleanups
Obsolete commented code deletion
Import and warning cleanup in CassandraThriftStore
Testing, import, and unused variable cleanups