Ensures to use at least sass 3.2.19

Fixes #656
Merge pull request #661 from magiclabs/fix/sass-dependency

Ensures to use at least sass 3.2.19
Update Tinymce to 4.1.6
Change the default behavior of the tinymce paste plugin.

The past as text option is now always enabled.
Merge pull request #662 from magiclabs/tinymce-update

Tinymce update
Merge branch 'master' into feature/json-api-namespace