Added blog post about go runner becoming the official one

@sytse What do you think?

See merge request !664

Updated applications supporting gitlab page to add SourceTree

This simply adds another program that supports using Gitlab with. Its my daily driver and was surprised to not see it on the page. Of course feel free to edit the description text.

See merge request !655

Blog post for omnibus patch releas 7.10.1.

See merge request !660

Security page

Made a page to begin documenting our security policies. Not linked from anywhere on the website yet.

cc @jacobvosmaer @dzaporozhets @Haydn

See merge request !657

Add ayufan to the Core Team

Added myself. Please let me know what do you think about the bio.

See merge request !658

Debian 8 pkgs

Suggested tweet: "GitLab Omnibus packages for Debian 8 are now available! <link to blog post> #gitlab"

See merge request !659

release 7.10.1

See merge request !656

GitHost blog post

/cc @JobV @dzaporozhets

See merge request !653