HBASE-9165 [mapreduce] Modularize building dependency jars

Separate adding HBase and dependencies from adding other job dependencies, and
expose it as a separate method that other projects can use (for PIG-3285,
HIVE-2055).


git-svn-id: https://svn.apache.org/repos/asf/hbase/branches/0.94@1542414 13f79535-47bb-0310-9956-ffa450edef68
Merge remote branch 'origin/0.94' into 0.94-gd
Merge remote branch 'origin/0.94-gd' into fb-YAHOO-325-0.94-gd