SCHEMA-368. Split shims for HBase 0.92 and HBase 0.94.

* Renamed cdh4mr1-bridge to cdh41mr1-bridge (CDH4.1-specific).
* Added cdh42mr1-bridge (CDH4.2-specific)
* Renamed hadoop1-bridge to hadoop1-hbase92-bridge.
* Added hadoop1-hbase94-bridge.

Added shim method for creating an HFile.Writer object.