Remove panel model.
Add Ad's controllers and models

* Add Banner, campaign and Ad models and controller.
* Add carrierwave for upload ad file.
* Add coffeescript in gemfile.
Add post model in dummy app for test.
Move ads admin controllers and views to /ads/admin/
first worked version.
Add stat model to to track ad's clicks.
Add devise for dummy app for testing.

Create user model to test authentication for ads/admin
Add authentication for Ads::Admin
Move coffeescript code to engine
Merge pull request #1 from ecleel/develop

Develop