admin: Fix outstanding issues for 0.16

This patchset resolves all the outstanding Admin issues for 0.16. These issues are:

- [Better Images presentation](https://github.com/apyrgio/synnefo/issues/292): Use Plankton backend to show more info about Images
- [Show more info in details](https://github.com/apyrgio/synnefo/issues/217): Add info that was previously only in the badges of an item, as entries in its details 
- [Present VM flavor properly in details](https://github.com/apyrgio/synnefo/issues/218): Instead of simply showing the flavor values, include their units and their resource names.
- [Remove stale files](https://github.com/apyrgio/synnefo/issues/287): Cleanup files that are no longer needed, mostly static files.