Migration support

### Steps
- [x] Migration support for Realm
- [x] Migration support for CoreData

### Documentation
http://www.informit.com/articles/article.aspx?p=2150667&seqNum=4
http://realm.io/docs/cocoa/0.86.0/

### Related issue
https://github.com/SugarRecord/SugarRecord/issues/31

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