New directory structure for Records

[xmichael]

Change PCAPI high-level /records/ REST call to use a new directory structure underneath. In the new structure the records will be grouped by survey id.

Example
/records/local/UUID/Name used to translate to /fs/local/UUID/records/NAME/records.json but now it should translate to /fs/local/UUID/records/SID/NAME/record.json instead.

The new structure is better suited to COBWEB's survey-based structure and security system and is crucial for enabling scalablility and overcoming namespace pollution in records of different surveys.

This change will break compatibility in FTOpen as::

• /records/ will require the SID as an extra parameter.
• FTOpen might already be using low level /fs/ calls for record access that will need to be rewritten to use /records/

This issue is a spin-off of cobweb-eu/cobweb#166

[gmh04]

The change for the app is in the cobweb-pcapi-43 branch of the sync plugin, but untested. I will test it once it is available in the pcapi.