cyclades: Fix type error

together with some PEP8 issues.
cyclades: Fix snapshots of attached volumes

Fix major bug when taking snapshots of non-root volumes. The custom
'SnapshotInstance' method of 'GanetiRAPIClient' always took a snapshot
of the root volume (index=0) of an instance, ignoring the volume that
the user requested. This resulted in always taking a snapshot of the
root volume which in many cases did not fail.
cyclades: Invalidate snapshots when job fails

Make Cyclades invalidate snapshots in case of failure to submit the job
to Ganeti, or when the job fails. In either case invalidation is
performed by marking...
TODO: Add states sto API

fixes grnet/synnefo#231
pithos: Restore PostgreSQL 8.4 compatibility

Change SQLAlchemy statement to generate SQL code that uses ||
concatenation operator instead of the 'concat' function
(inexistent in earlier PostgreSQL versions than 9.1)
burnin: Enable multiple uploads

Extend Pithos burnin tests to enable multiple file uploading
of various sizes.
pithos: Fix metadata copying