Refactor Ohouse config

[motine]

As discussed on the 8th of April:

• defaults.json moves to the plugin folder
• supplementary fields get their own file in deploy
• general config (e.g. Consider deployment specific configuration #19 or Configurable MongoDB instance #16) gets its own file in deploy
• we keep the configdb and configrpc for AMsoil/flask config
• the registry database gets its own file

Did I forget anything?

[motine]

Since this goes along with the other tickets (#19 and #16) let's do it all in one go.
Details for the bullets above (same order):

• find out which plugin uses defaults.json, move it there and adjust the code
• filename supplementary_fields.json and restructure the hash inside so that it does not contain redundancy
• filename config.json (may include the mongodb config), make sure to move the stuff which is in there currently first (registry and suppl. fields), including adjusting the code which uses that "old" code.
• ...
• filename registry.json