Changing cms structure

This pull request aims at making the Website use the Comfortable Mexican Sofa's database structure in a more efficient way.

We had too many 'Cms::Site' objects for the same site, and I believe that we should only have one 'Cms::Site' and then multiple nested pages.

The pull request adds a rake task to update the data in the database to match this. It is based on the ids existent in the current production database, so to test it you should use that database in your local machine.

The task to run is called:

**rake unepwcmc:refurbish**

After running this task, everything should work. :)

Let's test this properly before thinking of deploying it to production.