Removed repo_id column from collection management.

Since it's now a subrecord it shouldn't need it.
Remove :repo_id columns for other subrecord tables that don't use them
Always create a repository agent when creating a repository
Add support for transferring the following record types to a different repo:

  * Accessions
  * Resources
  * Digital Objects
Frontend changes for transferring accessions.
Changes for resource transfers
Changes for Digital Object transfers
Merge pull request #541 from hudmol/record-repository-transfer

Record repository transfer