Bump tinymce-rails from 4.7.5 to 4.7.6
Bump tinymce-rails from 4.7.5 to 4.7.6

Bumps [tinymce-rails](https://github.com/spohlenz/tinymce-rails) from 4.7.5 to 4.7.6.
- [Commits](https://github.com/spohlenz/tinymce-rails/commits)
rdunlop/unicycling-rulebook,rdunlop/unicycling-rulebook,rdunlop/unicycling-rulebook,rdunlop/unicycling-rulebook