Bug 1083780 - Update help links

This fixes Bugzilla bug [1083780](https://bugzilla.mozilla.org/show_bug.cgi?id=1083780).

Per Ed's suggestion I've updated the links at the top of the help page. In it I've:

* put them all inline which saves space
* referenced the Wiki as the first of those links
* added a 'Source and Docs' link (referenced anchor points to all 3 mozilla hosted repos)

I figure if we ever consolidate the treeherder-[service,ui,client] repos, we might only need to update the Wiki, and not necessarily this Help page.

Here's a before and after:

![helplinkscurrent](https://cloud.githubusercontent.com/assets/3660661/4689982/1e89617a-56d6-11e4-80dd-225463965399.jpg)

![helplinksproposed](https://cloud.githubusercontent.com/assets/3660661/4689983/23359860-56d6-11e4-9799-dc973c8eab34.jpg)

Maybe there are more we could add? If so let me know and I'll include them.

Tested on Windows:
FF Release **32.0.3**
Chrome Latest Release **37.0.2062.124 m**

Adding @edmorley for review.