Add clean target to RoboFile
Move cache folder around
Add assetic, cssmin, and silex-assetic to deps
Add new AsseticFilters
Remove gulp and NPM stuff
Remove gulp references in docs
Remove the gulp Robo task, add assets task
Add note in README about slow coverage reports
Ignore the .vimrc.local file
Change debug mode to a .env file param
Ignore everything in the cache dir for coverage
Make the RoboFile's clean task work correctly

Specifically with nested folders
Add CssMinFilter, but don't use it

Because it breaks font-awesome.
Update css / js blocks in document.twig
Update name of ignored JS file
Update travis conf, remove references to gulp
Move the .env file before running robo tasks
Move all .gitignore rules to the root one

Also amend them to ignore any of the style.min_xxx.css files that
Assetic dumps all over
Merge pull request #55 from purplapp/feat/assetic

Switch from Gulp to Assetic