Make Cyclades work with Archipelago v2 and Pithos
Recent commits have integrated Archipelago v2 mapfiles to Pithos. This commit updates Cyclades to go along with the recent changes in Pithos. Specifically, this commit makes the following changes: * Use the 'mapfile' attribute of the Pithos objects, instead of the old 'hash' attribute. Also, this attribute needs no custom prefixing ('archip:' or 'pithos:'). * Do not store 'is_snapshot' and 'status' attributes as plankton properties. The 'is_snapshot' attribute is now provided from Pithos. Also, the 'status' attribute can be derived from the 'available' attribute. * Remove code from 'snf-dispatcher' that used to update the 'status' plankton property when the OP_INSTANCE_SNAPSHOT Ganeti job completed. This functionality is now covered internally from Pithos.