Use data-target attribute if present on collapse

This patch fixes a JS error when the element with the attribute data-toggle="collapse" has a URL href (instead of a jQuery selector) and additionally a data-target attribute with the jQuery selector for the collapsible element. This is useful if you want to offer the opportunity to open the link in a new window (or even when JS is disabled).
Example: 
<a data-toggle="collapse" href="http://www.example.org/" data-target="#collapsibleElement>
  Collapsible Group Item #1
</a>
Merge pull request #30 from rwdaryl/patch-1

Use data-target attribute if present (Collapse extension)
Generating latest minified file
Ignore .sass-cache folder
Ignore DS_Store file
SASS Configuration
Deleting sass-cache from git
Removed other .sass-cache folder
Dividing all CSS in various SASS files and using SASS/COMPASS functions like mixins, variables and transition
Added minified and compiled files
Updated demo file to bring in sync with gh-pages.
Adding bower.json
updating PayPal Accessibility logo
Logo image updated with better left alignment
Merge pull request #31 from deblynprado/master

Add SASS to CSS
fixes #35 remvoing aria-expanded property for tab
Tab extension : support nav-pills
Merge pull request #36 from rohk/master

Tab extension : support nav-pills
Generate minified JS
Split plugin into individual files fixes #34