Adds a live preview feature for EssenceText and EssenceRichtext editors.
Adds content specific live update.
Adds Twitter Bootstrap CSS and disables preview window reload on element update.
Updates dummy app. schema
Update live editing events for Tinymce 4 API.
Select element editor on click of Tinymce text area.
Refactors the live update js code.
Moves the live preview functions into its own javascript module.
Implements picture live preview feature. WIP
Moves resize_url_options code from helper into essence_picture model.
Adds a preview_url method to admin/essence_pictures_controller.

That method generates the preview url after assigning or updating an EssencePicture.
Trigger select element event after clicking on essence_picture tool link.
Adds content specific live update.