Revision 643223

HBASE-505 Region assignments should never time out so long as the region
server reports that it is processing the open request

This is patch reviewed with Jim but with the number of edits between
reports made into a configurable.

Have the HRegionServer pass down a Progressable implementation down into
Region and then down int Store where edits are replayed. Call progress
after every couple of thousand edits.

M src/java/org/apache/hadoop/hbase/HStore.java
  Take a Progessable in the constructor. Call it when applying edits.
M src/java/org/apache/hadoop/hbase/HMaster.java
  Update commment around MSG_REPORT_PROCESS_OPEN so its expected
  that we can get more than one of these messages during a region open.
M src/java/org/apache/hadoop/hbase/HRegion.java
  New constructor that takes a Progressable. Pass it to Stores on construction.
M src/java/org/apache/hadoop/hbase/HRegionServer.java
  On open of a region, pass in a Progressable that adds a
MSG_REPORT_PROCESS_OPEN every time its called.