Add Template for Gap and Overlap Analysis
Add Template for Gap and Overlap Analysis

As discussed in the meeting[1], this commit proposes a template for gap
and overlap analysis.

[1] http://eavesdrop.openstack.org/meetings/product_working_group/2017/product_working_group.2017-01-16-21.00.log.html

Change-Id: I585f3094d9f44ec9f253f268cdbaf99233f9cf11

openstack/openstack-user-stories