Redesign interview logs

[kaligrafy]

Create a log table and class. This class should record, for ecah change in the interview data:

• device
• user agent/browser data
• ip
• timestamp
• interview language
• objectName (interivew, household, person...)
• attribute (attribute path in the object: example: age) (undefined if action = create or action = delete an entire object)
• action (create, update, delete)
• value (new value for update, undefined for delete) Any input on this? @tahini @greenscientist @samuel-duhaime

[tahini]

Related: #47

We should investigate external tools that could be used to do all this