Studio support for creating and editing libraries (PR 6046)

Duplicates https://github.com/edx/edx-platform/pull/6046 to allow Marco to review without spamming the reviewers on the original PR.
Same comment as for line 109 above. 
"The unique code that identifies this library. The code becomes part of the library URL, so no spaces or special characters are allowed. After you create your library, you cannot change the library code."