Tower + GitLab integration announcement & discount post

Announcement + Discount Post

In the style of the post you did with DigitalOcean (http://bit.ly/1U5B87m), I think there's room for a short piece that:

Celebrates the launch with a Tower discount code, exclusively for GitLab users.
Informs GitLab users about the tight integration in Tower, making repository management a great deal easier for them.