Allow short and long form references

Both `--task task_name` and `--task '{"name": "task_name"}'` should be accepted in create-repo. Previously, this was translating the client's request into JSON, so `--task task_name` would fail.

Fixes https://tickets.puppetlabs.com/browse/RAZOR-208
Fix navigation attributes

`create-policy` and `move-policy` were not properly converting their parameters using the new 'reference' type, which allows both short-reference and long-reference forms.