slapos_web: Improve the display of service list and hosting subscription (short title and description)

https://github.com/giampaolo/psutil/issues/451
( and other deprecated API were removed )

- Bug fix for firefox
- Load selected values on promises
-  Added support to items.

For now, it only generate entries for tickets.

List Ticket which are related to the Hosting Subscription and Computers (at web view)
Added a button to open a Ticket from Hosting Subscription and Computers (at web view)
Include RSS link generator (not exactly working yet)

This url allows us build easily a link (url) in order to request an instance from some external website.

this will expose default values which are wrongly inputed.

Failover should be render a textarea explaining the error.

This will enable edition of parameter using a JS editor.

This is a workarround to use the same version for gadgetfield at slapos website and the gadgets. There is probably a more clever way to do it after.