cyclades: Forbid deleting port from suspended vms

Check if a VM is administratively suspended before deleting it's port.
pithos: Refactor statistics subquery

Use CTE to get current population.

Add partial index to versions table.
pithos: Add missing setting from conf
pithos: Fix issues with groups

* Apply checks for group name/member length
* Do not try to insert an existing member to a group (integrity error)
pithos: pep8 fixes

closes grnet/synnefo#172
Update Cyclades section in Changelog
Fix typo
Bump version to 0.16next
astakos: Move code under synnefo.astakos.*
astakos: Update references
astakos: Update external references
cyclades: Move code under synnefo.cyclades.*
cyclades: Update references
cyclades: Update external references
branding: Move code under synnefo.branding.*
branding: Update references
branding: Update external references
pithos-app: Move code update synnefo.pithos.*
pithos-app: Update references
pithos-app: Update external references