Shifted the project's main stylesheet out into the `main_css` block, which allows it to more easily override lib css which tends to be dumped into `css`.
Cleaned up some mixed indentation in the comment block describing the different blocks available from ixc_core/base.html.
Changed the low-level elements to use classes rather than ids, and changed the selectors to be both more verbose and to use camel-case.
Cleaning up the base template's blocks.

Shifted the primary stylesheet back into the `base_css` block.
Wrapped the contents of the `head_js` block in a `{% compress js ... %}` tag.
Merge pull request #2 from markfinger/master

Base template changes