HBASE-12145 Fix javadoc and findbugs so new folks aren't freaked when they see them

Fix javadoc warnings.

Fixup findbugs warnings mostly by adding annotations saying 'working as expected'.

In RpcRetryingCallerWithReadReplicas made following change which findbugs spotted:

-        if (completed == null) tasks.wait();
+        while (completed == null) tasks.wait();

In RecoverableZooKeeper, made all zk accesses synchronized -- we were doing it
half-ways previously.

In RatioBasedCompactionPolicy we were making an instance of Random on
each invocation of getNextMajorCompactionTime
HBASE-12078 Missing Data when scanning using PREFIX_TREE DATA-BLOCK-ENCODING

Signed-off-by: Andrew Purtell <apurtell@apache.org>
HBASE-12120 HBase shell doesn't allow deleting of a cell by user with W-only permissions to it (Srikanth Srungarapu)
HBASE-12127 Move the core Connection creation functionality into ConnectionFactory (Solomon Duskis)
HBASE-12140 Add ConnectionFactory.createConnection() to create using default HBaseConfiguration. (Jean-Marc Spaggiari))
HBASE-12153 Fixing TestReplicaWithCluster (Manukranth Kolloju)
HBASE-12156 TableName cache doesn't used for once of valueOf methods (Andrey Stepachev)
HBASE-12152 TestLoadIncrementalHFiles shows up as zombie test; ADD TIMEOUT ON TESTS
HBASE-12133 Add FastLongHistogram for metric computation (Yi Deng)
HBASE-12158 TestHttpServerLifecycle.testStartedServerWithRequestLog goes zombie on occasion
HBASE-12149 TestRegionPlacement is failing undeterministically (Manukranth Kolloju)
HBASE-12133 Add FastLongHistogram for metric computation; ADDENDUM TO FIX BROKE COMPILE
HBASE-12148 Remove TimeRangeTracker as point of contention when many threads writing a Store
 HBASE-12148 Remove TimeRangeTracker as point of contention when many threads writing a Store
HBASE-12152 TestLoadIncrementalHFiles shows up as zombie test; ADD TIMEOUT ON TESTS -- Up timeout from 120 to 120000
HBASE-12122 Try not to assign user regions to master all the time
HBASE-12160 Make Surefire's argLine configurable in the command line