fixed installation

the install process was broken and should be fixed now.

failed attributes and Attribute aliases

• Models will now hand over failed attributes as a list to the ValueError when raising which should make error evaluation easier.
• Attributes now allow an alias as kwarg, this should make version transitions for Models easier (e.g. user -> username will still work for data

fixed local package version

fixed problem with installed package not being versioned.

fixed premature raise

Exception for failed Attribute initialization were raise prematurely.

persistent attributes

Model attributes will now be stored persistently. This will allow you to use names like '@foo' for attributes in de-/serialization.