[FIX] Allow registrars to access/modify registrant
[IMP] MaKaC.common.Configuration -> indico.core.config

 * Solves some circular import issues too
[ADD] backbone, modenizr and polyfill
[FTR] WYSIWYG Registration form

   * WYSIWYG registration form
   * Page rendered on client side
   * HTML5 Validation
   * Position changes can be done with Drag-and-drop
   * Single page for editing of the registration form
   * Radio group buttons can be now ordered by the user
[DEL] previous version of the registration form
[IMP] Better field chooser
[FIX] After flask rebase fixes
[IMP] Update webshim, backbone, jquery-migrate

- Added backbone to ext_modules
- Added webshim to ext_modules
[REF] Move RegForm CSS to SASS folder

- PEP8
[FIX] Several fixes

- Backbone views initialization
- New toolbar
[REF] Moved registration fossils to core
[FIX] RegForm display rendering process
[FIX] Several fixes

- Backbone views initialization
- New toolbar
[IMP] RegForm: CSS cleanup
[IMP] RegForm: HTML cleanup

Removed unnecessary <table> elements
[NEW] Added Nunjucks for JS templating
[MIN] Set ext modules to latest stable release
[IMP] RegForm: TPLs ported to Nunjucks
[FIX] RegForm: Moved logic out templates
[NEW] Added Angular.js as submodule