Ported build to jbuilder.

Merge pull request #69 from kc284/master

CP-26711: Ported xapi-storage to jbuilder.

Upgrade to Foundation 6.2.1

This release captures mainly the upgrade of the HTML framework Foundation to 6.2.1.

Fix json error encapsulation

• Fix json error encapsulation

Clean up logging

• Clean up xapi.storage.log log-entries

Python improvements

• improved package structure

Lots of API improvements

• support for RRD datasources
• support for SR name and description
• support for SR probe

Add optional volume uuids

Storage implementations which have a natural uuid can now supply it, which will allow higher layers (i.e. xapi) to see and use the uuids.

Clone on boot

• Store metadata with volumes with Volume.set and Volume.unset
• Support non-persistent data paths with Datapath.open and Datapath.close

Volume set_name set_description and physical_utilisation

• allow the plugin to persist a name and description per Volume
• add physical_utilisation to Volume.stat

Update SR.stat

• SR.stat uses total_space and free_space