[glesys] Attributes were overwritten when getting server details

Attributes were overwritten when requesting full information about a
server. Essential the problem is that both the server details and the
server status were requested from Glesys then merged together to create
a Fog Glesys server model object. I moved some of the status attributes
into a usage attribute on the server instead.
Merge pull request #1552 from smgt/glesys-server-attribute-fix

[glesys] Attributes were overwritten when getting server details