ACCUMULO-3388 Ensure that DefaultMetricsSystem is only initialized once.

Use the initialization-on-demand holder idiom to make sure that we
only have one instance of the MetricsSystem per process.
ACCUMULO-3306 Simplify PortUtils.getRandomFreePort

Remove the computation of a "random" port number
and just use the OS provided feature of asking
to bind the socket on '0'. Fixed a bug where
the count variable was not incremented.
ACCUMULO-3308 Expand docs on configuration of IMM.

Expand on how the minc threshold, IMM size and WAL size
must be altered together. Additionally, mention how
the HDFS block size for the WAL should be increased to 2GB
when the WAL size is increased over 2GB.
Merge branch '1.6'

Conflicts:
	docs/src/main/latex/accumulo_user_manual/chapters/administration.tex
ACCUMULO-3308 Clarify WAL block size recommendation.
Merge branch '1.6'

Conflicts:
	docs/src/main/latex/accumulo_user_manual/chapters/administration.tex
ACCUMULO-3392 Remove incorrect javadoc on MiniAccumuloCluster.start()

Also fixed the impl's javadoc.
Merge branch '1.6'
ACCUMULO-3269 Set REUSEADDR on the Socket.

Setting SO_REUSEADDR on the Socket used to ask
ZooKeeper if "it's ok" appears to help mitigate
the spurious issue when ZooKeeper would fail to
bind to an otherwise free port.
ACCUMULO-3381 add accumulo-trace back into assembly
Merge branch '1.6'
ACCUMULO-3306 Remove unused import
ACCUMULO-3269 Add a brief sleep before retrying ruok
Merge branch '1.6'
ACCUMULO-3394 Consolidate thrift related classes in one package.
ACCUMULO-3394 Remove unused method.
ACCUMULO-3394 Update some documentation.
ACCUMULO-3394 Fix up whitespace
ACCUMULO-3394 Change thrift package to rpc and make an rpc package in core too
ACCUMULO-3395 Keep a reference to a single Logger instance.