Feature/milestone3

[windoverwater]

Not completely working but milestone 3 is close enough. Ended up with several design significant refactoring changes:

• changed the low-level ballot format (and config.yaml format) such that the contests node of the ballot data model is an array instead of a dictionary.
• the ElectionConfig is now a real singleton pattern - it is only every created once per election
• created a real webapi class to hold functions for that
• the ballot receipt is now stored as a bare csv file and not a markdown
• the QR svg is now being passed back to the client side (incorrectly but at least passed back)
• the Operation class is no longer a singleton

This was done to support milestone3 features in the client side