Type classes should not need to extend the AbstractAnnotatedObjectType

[moufmouf]

In order to make graphql-controllers independant of youshido/graphql (since it is abandonned), we should be able to create types that do not need to inherit any class (and in particular the AbstractAnnotatedObjectType).

• Add a @SourceField() annotation that can live in the class docblock to quickly expose existing properties
• Write a class that transforms a random instance of any class into a GraphQL type by analyzing its annotations
• Write a package that scans a directory and returns all its classes
• Write a TypeMapper that scans a directory, analyze a @type annotation that performs the Type to GraphQL type mapping

[moufmouf]

Closed by #33