SQOOP-611. add the --hbase-timestamp-column option while importing the data into HBase from tranditional database.

one bugfix: HBaseImportMapper modified to support import the blob column to hbase
Add the --bulk-load-dir option to support the HBase doBulkLoad function
Revert "Add the --bulk-load-dir option to support the HBase doBulkLoad function"

This reverts commit 16823d13e102fdc766d7e58c581b97d08ea1a29e.