baseldap: Properly handle the case of renaming object to the same name

When renaming a object to the same name, errors.EmptyModList is raised.
This is not properly handled, and can cause other modifications in the
LDAPUpdate command to be ignored.

https://fedorahosted.org/freeipa/ticket/4548
idviews: Fix casing of ID Views to be consistent
idviews: Make description optional for the ID View object
idviews: Add Default Trust View as part of adtrustinstall
idviews: Handle Default Trust View properly in the framework
idviews: Make sure the dict.get method is not abused for MUST attributes