Pin loaders requirements

1. Database change: add the is_data_loader field to the users table, using the sentence at the end of the DB schema creation script.
2. Create and mark users as data loaders in the admin:
/admin/edituser/5
/admin/createuser
3. When data loaders login, they go direct to the data load page
4. Data loaders have a link in the plus (+) menu to the data load page (only for data loaders)
5. Data loaders now has 2 tabs: load and added. You can see detailed information of each attempt to load data.
6. For page /register/after-signup/2 there was a bug that some times the 'get it' button didn't show. Also the order for the image load in the page was not natural.