Added callback functions for avoiding simultaneous editing of documents and documents lists (callback functions both call _manage_edit_state())
Add checkbox column in lists, add comments, reorganize code
Update to Grocery_CRUD 1.4
Remove whitespace from filename
Fix some bugs
Adapted code for designing the GUI, added a footer
Adapted GUI to CI of University of Zurich, added logo and customized styling information
Merged styling information (conflict with updated file)
Update Grocery_CRUD to a modified version

The modified version implements callback_can_edit as
steveoc has implemented it before.
Finished views except two little issues in list view of GroceryCRUD (table width too big for small browser windows and position of sorting arrows in checkbox column). Did some small changes in controllers to display appropriate messages and buttons to user in views. Admin view has not been touched.
Adapt models and mappers to new database structure

Document_models and Document_list_models can now have
several admins. Creator and admins are loaded as User_models.
Add handling of possible concurrent edits, add preview, autogenerate explicitId

- Only one user at a time can edit an entry now
- Value for field explicitId can now be generated
- A (mock) preview field shows, how the bibliographic entry of
a document will look.
Added validation rules for user entries
Added one validation rule for document edit mask
Add handling if a list doesn't exist.
Fix bug in check_edit_permisssions_documentlist
Don't write fields created and creator to db.
Merge branch 'crud' of https://github.com/ELK-Phil-UZH/roselit into crud

Merge was necessary because several people have been working in the
branch crud.

Conflicts:
	application/libraries/crud_service.php
Add routes for file handling
Autoload helpers url and html