Add links to the quick help list
Add links in the quick help list to the pricing and feature comparison pages on about.gitlab.com. See #1969
cc @sytse
See merge request !1525
Avoids an empty Sign in box when signup_enabled? is false, and avoids
showing "No authentication methods configured" unless there really are none.
OmniAuth signin gets its own file for consistency with signin and signup and LDAP.
Allow users that signed up via OAuth to set their password in order to use Git over HTTP(S)
See #1982.

There's a similar tooltip for SSH: "Add an SSH key to your profile to pull or push via SSH". These are always shown on-hover, even if the persistent flash above was hidden.
cc @sytse
See merge request !1512
Prevent autogenerated OAuth username to clash with existing namespace.
If the OAuth username already exists as a group rather than a user, automatic account creation would still fail.
See merge request !1511
Test settings for issue tracker service
This adds minimum logging and response when using "test settings" button when the service is enabled.
See merge request !1506
Add tracker integration doc and help page on service
Added documentation on how to enable tracker integration. Fix the active link on the admin page. Added help under the JIRA service page.
See merge request !1508
Add headings to signin/signup blocks on signin page.
See #1986

When signup is disabled, the heading for sign in only reads "Sign in", because there is no longer a choice of Existing/New user.
I've moved the OAuth signin options to just below the signin box because it looked odd as a separate box without a heading.
cc @sytse
See merge request !1516
Don't allow page to be scaled on mobile and add horizontal scrolling to code blocks
Closes#1974.
Previously, scaling (both automatically and manually) was enabled on mobile, which caused the top and sidebar to move over content. Scaling is now disabled.
Also previously, code in issues or comments too wide to fit inside the width of the window would "flow out" on the right, causing the whole page to become very wide and causing scrolling to scroll the entire page instead of just the code. Code blocks now scroll themselves.
See merge request !1501