try to detach from Bootstrap

[afeld]

Was talking with @andrewmaier today about the plugin, and realized that the only part of Bootstrap that this plugin relies upon (I think) is Scrollspy. Would be useful to try and list the dependencies more explicitly, so that it can be easily used outside of sites with Bootstrap.

[afeld]

Pretty sure Scrollspy can be used standalone, but that would be something to test:

• https://github.com/twbs/bootstrap/blob/master/js/scrollspy.js
• http://getbootstrap.com/customize/?id=5000ef8619d4208de45b

Since Bootstrap docs don't make that explicit, would be good include in the updated instructions.

[afeld]

CSS classes in use that use styles from Bootstrap:

• .affix
• .nav