Ensure no double slash in get token URL

Before appending a slash to an URL, we should make sure
that the url doesn't already have one at the end.

Change-Id: Iff864d9b49cf3e3138f602a2c6615ed742f35698
Closes-Bug: 1337880
Add CRUD operations for Federated Protocols.

Add relevant methods for adding, updating, listing, getting, and deleting
Federated Protocol objects.

Change-Id: Ibd8488158619d1689fbdfe21df114433c41c91f8
Implements: blueprint federation-crud-operations
Merge "Add CRUD operations for Federated Protocols."
Merge "Ensure no double slash in get token URL"