Swap out application.css for application.sass

Without our own application.sass file, we were barfing on undefined
varialbles in _network.sass if it happened to be loaded before the
framework was up.
Merge pull request #151 from VictorLowther/pull-req-master-b315146a56209cc5b6a07cb05124133c40dca602

Merged by devtool for cloudedge