Migration per application and on core

This pull request allows migration per application and on core.

Here are precise features :
* Migration per application : supports migration files on application migrations folder
* Migration on core : supports migrations files framework/migrations
* Supports same migration name on different application (migration files are on application namespace instead of `Fuel\Migrations`)
* Migration are executed when clicking on install button in the application manager (works for core / application / local)
* Detects if application / core / local is on last migration and shows the "Apply changes" button if not (it will execute the migrations)
* Simply supports updates from older version : if you update from an older version, the application manager will ask you to apply changes.

Please feel free to test on your own instances : pull, then go to your application manager. Only local migrations are not deleted here since it is on novius-os repo (so it will ask you to apply changes on local, but don't do it).

When pull request is accepted, I will merge novius-os repo. It would be quite complicated to post a pull request on this repo since I also updated local applications.