remove dep on tinymce-builded, newer tinymce

Remove bower dependency on ``tinymce-builded``, since the ``tinymce`` dependency already points to the official builded ``tinymce-dist`` reposotory. Raise TinyMCE version to 4.1.6.

+ add a CHANGES.rst file to maintain changelogs. i *like* changelogs. we might update it with previous changes at a later point...