[master] Add wait interval to region reopener.

Author: shaneh

Summary:
Added wait interval to region reopener and exposed it to the shell
commands.

Test Plan:
Created test table and confirmed the wait interval and concurrently
closed regions parameters were respected.

Reviewers: liyintang, nspiegelberg

Reviewed By: nspiegelberg

Differential Revision: https://phabricator.fb.com/D741859

git-svn-id: https://svn.apache.org/repos/asf/hbase/branches/0.89-fb@1466167 13f79535-47bb-0310-9956-ffa450edef68