[master] Make HFileOutputFormat able to write Hfile for bulk uploading without integration to MR

Author: fan

Summary:
Make HFileOutputFormat able to write Hfile for bulk uploading without integration to MR.
Only change is adding a new method to HFileOutputFormat so there is no affect to original code path.

Test Plan: A new unit test combined HFile writing and bulk uploading.

Reviewers: adela

Reviewed By: adela

CC: hbase-eng@, lesha, aaiyer, manukranthk, rshroff, gauravm

Differential Revision: https://phabricator.fb.com/D1006580

Task ID: 2998391

git-svn-id: https://svn.apache.org/repos/asf/hbase/branches/0.89-fb@1531568 13f79535-47bb-0310-9956-ffa450edef68