fix model typing
add belongs_to association. update serialization support
fix associations class inferrance to avoid cyclical dependencies
Merge branch 'master' of github.com:Voyst/arke into release/0.2.0
Merge branch 'develop' of github.com:Voyst/arke into release/0.2.0
Merge branch 'develop' into release/0.2.0
added build method to build users