Fix -import<relationship> called before -shouldImport<relationship>

Also removed establishRelationship block; not needed.
Previous implementation of this method would call
-shouldImport<relationship> AFTER `-import<relationship>`, and in
addition `-shouldImport<relationship>` was called with every object of
a to-many relationship passed in.
I'm a little bit concerned by the unnecessary changes in whitespace formatting. I know this is probably just an oversight, but its good form to use the existing style used throughout the project. We provide a clang format configuration for the project that can help with this, as well as documentation in the wiki: [MagicalRecord Coding Conventions](https://github.com/magicalpanda/MagicalRecord/wiki/Coding-Conventions).