Made the migrations to be stored inside the database and now they are be...

...ing executed in the correct order asweel, sorted by timestamp. Also made this class comply with OXID coding standards

As requested :) Ran it against the OXID coding standards that can be found here ¹ without any erros.

[1] https://github.com/OXID-eSales/coding_standards
OXID Console, not OXID eShop Community Edition