ACCUMULO-3066 Allow credential providers to be used with ClientConfiguration.

When the general.security.credential.provider.paths is set in the
ClientConfiguration, any Sensitive properties defined within will
used instead of any other defined configuration value.
Merge branch '1.6.1-SNAPSHOT'
ACCUMULO-3068 Add create/flush methods to CredentialProvider, configure ITs with CP too.

Add some more reflection to work create and flush CredentialProviders. Changes
MAC to add support for using a CredentialProvider for Sensitive properties.
Merge branch '1.6.1-SNAPSHOT'
ACCUMULO-3069 Make MACITest more resilient to tservers gradually starting
Merge branch '1.6.1-SNAPSHOT'
ACCUMULO-3070 Use dynamically set log4j port and not hard-coded.
Merge branch '1.6.1-SNAPSHOT'
ACCUMULO-3071 Add replication thrift service ports to user manual default ports.
ACCUMULO-3072 Split the test into multiple methods and use proper assertions
Merge branch '1.6.1-SNAPSHOT'

Conflicts:
	test/src/test/resources/log4j.properties
ACCUMULO-3021 Added constraint for max size of end rows

Signed-off-by: Keith Turner <kturner@apache.org>
ACCUMULO-3073 Increase the timeout a bit more
ACCUMULO-3074 Increase the timeout for MergeIT#mergeTest
ACCUMULO-3076 Increase the timeout for SimpleBalancerFairnessIT
ACCUMULO-3075 Increase SSL IT timeouts across the board

Most of the tests copied the same timeout as the underlying
IT they call. This isn't realistic as running with SSL is
typically going to be more costly.
Merge branch '1.6.1-SNAPSHOT'
ACCUMULO-3080 Remove debug logging from invoker-plugin configuration.
Merge branch '1.6.1-SNAPSHOT'
ACCUMULO-3077 Set StatusCombiner on accumulo.metadata during initialize.

Before mutations are written to the metadata table to
track replication, the configuration for the metadata
table is checked to ensure that the Combiner is set
(to make sure that the state is appropriately managed).

Because we cache ZK data and update it via Watchers, it's
possible that a tserver compacts some data after it was written
before seeing that the Combiner was set, effectively destroying
the older versions (VersioningIterator).

Setting the Combiner at init for the metadata table
does a better job at eliminiating this possibility.