Issue #1651740 by jcisio: Fixed MEE Resource Manager does not update when atom is not embedded in field.

Previsously, the "administer scald" permission controlled access
to both the atom edition and the atom types configuration.

The permission got split in two
- "administer scald" still controls the access to the atom types
  configuration and the different settings form.

- "administer scald atoms" is the equivalent of the "administer nodes"
  permission for the node module, and grants access to the overview
  of all atoms and a few more fields on the atom edit form.

The view was still configured to check the "use scald" permission,
which doesn't exist anymore in D7. Thus, only administators could
access the library, that's no longer the case.

Now that anyone can access the library, we also check if they're
allowed to create an atom of this type before showing the quick
add button.

- Fix the title of the full context
- Add an 'hidden' property to the definition of system contexts