Remodel soledad u1db couchdb backend so it's concurrent.

  • Store a u1db document's conflicts and transactions inside the couch document.
  • Use couch's view and list functions to retrieve metadata.
  • Use couch update functions to selectivelly insert metadata, as sync and transaction info.
  • Find a way to handle indexes wisely.

(from redmine: created on 2013-11-13, closed on 2013-12-19)