Implement Pagination for Content libraries

Jira Issue: SOL-4

Provides pagination for content Libraries in the Studio Editing View.

* Partner information: 3rd party-hosted open edX instance, for an edX solutions client (so will need to get some sort of solution merged in)
* Merge Deadline: Next Week, 11th of December
Looks like incorrect indentation. Please make sure pep8 and pylint does not report it. Also, it just doesn't look nice :)

One more thing - if I understand right general approach is to use named pylint errors, as looking at E1101 tells nothing what was that. Please replace with appropriate named switch.