Sidekiq improvements

[andreareginato]

Right now if the queue system is not working we loose the changes. Actually there is no easy way to restore them. For this reason we need to add a scheduled operation (sidekiq allow this) that check all types not taken in consideration for any reason. The flow to implement is this.

• add a new field worker_status to the type model
• it can have 3 states: ready, running, finished
• when a change happens the type is set to ready
• the worker take it up and set the status to running
• when the task is completed the worker set the status to finished

Now, if something goes wrong with the queue, we simply set the chron task to check every minute which types have the worker_status set to ready. Only if a type has changed and is not taken into the queue.

NOTE types are not going to be defined too often and they are usually fixed. So, make those changes only if really needed. In that case think at the whole flow.
NOTE This issue will take 1/2 days.
NOTE make things idempotent.