Revision 1006219

HBASE-3100 TestMergeTable failing in TRUNK

M src/test/java/org/apache/hadoop/hbase/HBaseTestingUtility.java
  Some fixup to support stepped start up of mini cluster; allow
  starting dfs cluster, then later put an hbase mini cluster on top.
  (startMiniHBaseCluster, createRootDir): Added. 
D src/test/java/org/apache/hadoop/hbase/AbstractMergeTestBase.java
  Removed messy subclass of HBaseClusterTestCase used building
  up some specific loaded regions.  Replaced with utility added
  to HBaseTestingUtility and by methods added to specific test.
D src/test/java/org/apache/hadoop/hbase/util/TestMergeMeta.java
  Deleted test that did nothing -- test merging of .META. -- but
  the superclass was making user regions, not multiple instances
  of .META. -- which we don't support anyways currently.
M src/test/java/org/apache/hadoop/hbase/util/TestMergeTable.java
  Rewritten to use HBaseTestingUtility.  Also added assertions that
  it actually did successful merge (Were none previous).
M src/main/java/org/apache/hadoop/hbase/catalog/CatalogTracker.java
  Added a new constructor.  Are the others redundant given I just
  added implementation of Abortable to HConnection interface (the
  implmementation of HConnection used implement it -- I've just
  moved it up into the Interface itself).
M src/main/java/org/apache/hadoop/hbase/util/HMerge.java
  Bit of minor cleanup refactoring.
M src/main/java/org/apache/hadoop/hbase/client/HConnectionManager.java
  The HConnection Interface now implements Abortable.
M src/main/java/org/apache/hadoop/hbase/client/HConnection.java
  Extend Abortable (The implementation was implementing Abortable
  anyways).