Ignore generated CSS files in the repository tree
Make sure a more recent compass is present by installing as a gem

This is based on sayit.mysociety.org's post_deploy_actions.bash

We also explicitly install compass's dependencies, since for some reason
I can't fathom at the moment, they aren't being installed automatically.
Strip some trailing whitespace
Make sure there are no newlines before the doctype

While newlines are allowed before the doctype, [1] this will make
older versions of IE switch to quirks mode, so it's best to avoid it.

[1] http://www.w3.org/TR/html-markup/documents.html#conformant-documents
Ensure that pombola_run_when_document_ready is defined before use

The extra_js URLs were being loaded before
pombola_run_when_document_ready was defined - this meant that a file
like map.js, which tries to call pombola_run_when_document_ready would
error.  This commit makes sure that it's defined before any of the other
Javascript runs.