admin: Add charts for cyclades/astakos

Add the following charts using the astakos/cyclades stats API:

* Total Resource Usage
* Resource usage per provider
* User status per provider
* Providers per user status
* Exclusive users per provider
* Servers status
* IP allocation status
* Disk templates
* VMs from images

This tackles apyrgio/synnefo#16 but doesn't totally fix it.