Bump VERSION to 3.3.7.
Move listen loading to Sass::Util so Compass can use it.
The reject method doesn't have a side-effect.
Merge pull request #1244 from chriseppstein/listen_loading_refactor

Listen loading refactor
Clean up and normalize function documentation.
Merge branch 'stable'

Conflicts:
	VERSION
	doc-src/SASS_CHANGELOG.md