[issues-45] Removes compass' clearfix

This will make this mixin less opinionated about how to clear the
parent container. This does mean that the responsiblity for
clearing will fall to the CSS author. With the remove of clearfix
the overflow property is added back in when calc is not supported.
[issues-45] Updates the examples pages.

Examples now reflect the new changes.
Merge pull request #49 from leadiv/issues-45

[issues-45] Remove clearfix
Merge branch 'develop' of github.com:leadiv/column-policy into issues-48

Conflicts:
	examples/stylesheets/attribute-columns.css
	examples/stylesheets/basic-columns.css
	examples/stylesheets/ie-columns.css
	examples/stylesheets/multiple-layout-columns.css
	examples/stylesheets/set-columns.css