Properly aligns compassBootstrap.default to the wording of the message

`(as opposed to vanilla CSS)?` seems to imply that the default would be vanilla CSS, so this changes that default to match that expectation.

The goal of this pull request is to try and better align `generator-angular` for cross platform support _as a default_, as it stands now if users don't take the time to read through the prompts, `generator-angular` sets up Compass/SASS by default on platforms where it is non-trivial to setup Ruby (lookin' at you, Windows) ;)