ACCUMULO-955 Made BatchWriterConfig Writable, so it can be stored in a job's configuration in a human-readable way. Updated AccumuloOutputFormat to use it, and
added unit tests for ACCUMULO-706 and ACCUMULO-955. Added an additional check for a reasonable minimum maxMemory value.


git-svn-id: https://svn.apache.org/repos/asf/accumulo/trunk@1435013 13f79535-47bb-0310-9956-ffa450edef68