3.0 translate behavior - First round

This PR addresses the basic functionality for the Translate behavior. So far it only handles the find operation under two different modes:

* Merge fields: From a single translation merge the fields into the main entity. Calling `$table->locale($language)` is required for it to work
* Put all translations into a property for each entity. This is done by using the `find('translations')` method and replaces the `bindTranslations` method from 2.x which was difficult to use, imo.

### Next steps:

* Make saving work
* Make fetching translations for belongsTo and hasOne work