Add a not operator.

Fixes #23
Run gulp without requiring global install
Remove unneeded Ruby Sass setup
Merge pull request #33 from envato/not_operator

Add a not operator.
update asset gulp instructions
Merge pull request #36 from envato/local-gulp

Local gulp
Merge branch 'master' into feature_settings_reactify
Remove srcmaps

- Killing some gulp sass builds
Merge pull request #37 from envato/kill_src_maps

Remove srcmaps
Merge branch 'master' into feature_settings_reactify