github-commit-link: Loosen regexp to match 7-through-40-char hashes

Instead of 7-or-40-char hashes (e.g. not 8-character hashes).  The
{m,n} syntax is part of POSIX's basic regular expressions, although
POSIX uses \{m,n\} [1].  It looks like CoffeeScript also supports this
range syntax [2]:

  | \.{2,3}           # range or splat

but I couldn't find a clear regexp specification while skimming the
CoffeeScript docs.

[1]: http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap09.html#tag_09_03_06
[2]: http://coffeescript.org/#regexes
github-commit-link: Add support for repo@<SHA> and user/repo@<SHA>

Based on similar parsing in github-issue-link.coffee.  The main change
in the logic is that the initial .* is now the non-greedy .*?, so it
doesn't gobble up the repo-part of the regexp [1].  The user/repo
portion is [^\s@]+, which matches one or more characters that are
neither whitespace [2] nor @.

The non-capturing (?:...) block [3] around the optional repo@ or
user/repo@ qualifier allows us to group the qualifier with its @, even
though we only need the repo or user/repo (without the @) in our
internal logic.

I use CoffeeScript's block regular expressions to comment the regexp
[4], and CoffeeScript's existential operator '?' to check if
'msg.match[1]' is defined [5].

I also document the fact that lines matching 'commit/' are ignored.

[1]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Regular_Expressions#special-questionmark
[2]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Regular_Expressions#special-white-space
[3]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Regular_Expressions#special-non-capturing-parentheses
[4]: http://coffeescript.org/#regexes
[5]: http://coffeescript.org/#operators
github-commit-link: Only show the first line of the commit

This is traditionally the message summary.  From Git's own docs [1]:

> The first line of the commit message should be a short description
> (50 characters is the soft limit, see DISCUSSION in git-commit(1)),
> and should skip the full stop.

I sometimes write long, detailed commit messages (like this one), and
there's no need to spam the channel with all of this motivational
background.  The summary line should be sufficient context there, and
folks looking for more information can follow the URL (which I've
moved to it's own line).

[1]: https://github.com/git/git/blob/v1.9.0/Documentation/SubmittingPatches#L89
Script deprecated. Provide warning and fail fast.
Remove the dependency to gitio

I just had a hard time debugging this, with removing that dependency it is way more stable then before.
better logging to support custom prefix
better English
Added South Park Bank Teller and Morpheus What if I Told You.
Fix error in github-pull-request-notifier when body is empty.

When someone submits a pull request without a message the JSON
document contains `null` for `body`. The notifier script was
trying to call `match` on `body` to extract the list of user
mentions. That would fail when it was `null`, resulting in:

    Whoa, I got an error: TypeError: Cannot call method 'match' of null

This changes it to use the existential access operator, so
when body is `null` the mention list is `undefined`.
Removed 404 images and added replacements to beerme.
Change description to read beer advocate script is broken rather than deprecated.
Merge pull request #1438 from nesQuick/patch-2

Remove the dependency to gitio from travis.coffee
Merge pull request #1436 from whyjustin/Remove_Broken_Beer_Advocate

Remove Broken Beer Advocate Script
Merge pull request #1446 from therealklanni/master

Better logging for custom prefix
Merge pull request #1447 from ericjsilva/master

Added South Park Bank Teller and Morpheus What if I Told You.
Merge pull request #1364 from wking/github-commit-link

github-commit-link: Support user/repo@SHA and shorten response
Merge pull request #1450 from Elemecca/t-github-notify-error

Fix error in github-pull-request-notifier when body is empty.
Merge pull request #1451 from fleeting/patch-1

Removed 404 images and added replacements to beerme.
Spelling fix
Merge pull request #1457 from kendaleiv/patch-1

Spelling fix