Define data model for Opora

[KrzysztofMadejski]

In a separate repo, ie. moonsheep-opora define data model for Opora including following entities:

• report (party, year or maybe also month.., link to document, pages with relevant data?)
• party (political one!)
• transaction
• payers

Here are data definitions: https://drive.google.com/drive/u/0/folders/0B36dZ7o6-vz3X1BlZzAwVE96b0U

It would be a specific implementation of #57 configuration flow.