add support for easy deployment of dtfabric yaml files in Python

[joachimmetz]

Handling data files in Python is not optimal. Having large yaml strings in Python files is not optimal.

Per https://codereview.appspot.com/328230043/ have an easy deployment of dtfabric yaml files in Python

• Wrap yaml in Python "envelopes"
• generate these "envelopes" or code based on the yaml files

[joachimmetz]

best solution for now is to package them as package data files, also see: https://codereview.appspot.com/334640043/