Fixed affixes with offset-bottom when html,body{ height:100% }

Created by: seven7seven

When using html,body { height: 100%; }, the affix plugin got confused of the document's height.

This resulted in flickering of the affix back and forth, incorrect classes and basically just a very sad affix.

See:

• https://github.com/twbs/bootstrap/issues/7414
• http://stackoverflow.com/questions/18379800/boostrap-3-affix-plugin-stops-working-when-body-100