Retry RPC at RegionMovedException.

The bug was that OpenTSDB/asynchbase did not recognize
org.apache.hadoop.hbase.exceptions.RegionMovedException when HBase 0.96 raised
it. It was converted to unknown RemoteException, and the corresponding queries failed.
The fix was retrying the HBase RPC requests like NotServingRegionException.
In AsyncHBase we use a timestamp instead, e.g. 1411787803 or something like that.