Add support for the Storyboard issue tracking system integration

This implements the ability to add comments to storybaord task tracking
system[1][2]. Updating of story status will be implemented in a follow
on change.

[1] https://wiki.openstack.org/wiki/StoryBoard
[2] http://git.openstack.org/cgit/openstack-infra/storyboard
Change-Id: If25ec21d4b89ef82dfef3d5f1f2dec1cc8294005