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

Author: wking

src/scripts/github-commit-link.coffee

@@ -28,7 +28,7 @@
 
 module.exports = (robot) ->
   github = require("githubot")(robot)
-  robot.hear /.*(\b[0-9a-f]{7}\b|\b[0-9a-f]{40}\b).*/i, (msg) ->
+  robot.hear /.*(\b[0-9a-f]{7,40}\b).*/i, (msg) ->
     if process.env.HUBOT_GITHUB_REPO && process.env.HUBOT_GITHUB_TOKEN
       if !(msg.message.text.match(/commit\//))
         commit_sha = msg.match[1].replace /\b/, ""