DDF-804 - Adding the new SourcesPlugin for the catalog sources tab.

* Fix Sources UI so it uses new templates and shows in the catalog tabs.
* Sources can be added and edited
* Clicking the source row will open the edit dialog
* Dynamic add/edit form generation
* Added new template for checkbox style options
* Added LESS to the catalog project
* Added the + and refresh buttons back to the sources view page.
* Added client-side check to prevent adding two source configurations with the same name.
* Source name is now editable and updates all existing configurations.
* Added checks to ensure that newly chosen name does not conflict with existing names
I changed the rendering code to use a method similar to the one in ddf-admin and moved templates over where appropriate.