SchemaShell --name and --file params priority fix.

Corrects the two issues identified by #4174 and CakeDC/migrations#183.

I don't currently have the proper test environment set up to run the core test suite locally, so I'm going to let Travis check things for me. I wouldn't be surprised if there is a test to fix somewhere.
Probably not all code has yet been updated, see examples:
http://book.cakephp.org/2.0/en/contributing/cakephp-coding-conventions.html#typehinting

If you want, you can make a PR in which you update these.