load cloud instances in a separate thread
keep track of instances by id, better add/update/remove handling
Merge pull request #16 from planctechnologies/gns-35

Gns 35 - Make polling run on its own thread
retrieve instance flavor from Rackspace provider
handle connection error when IAS is down
changed settings names for cloud instances size
select instance size with a combobox containing size (flavor) labels
handle new settings for flavor/size values
fixed tests
removed import from string, hardcoded RackspaceCtrl instead
Merge branch 'dev' of github.com:planctechnologies/gns3-gui into dev
Merge pull request #17 from planctechnologies/gns-34

Supply instance flavor descriptions
Remove pricing label from cloud preferences pane.
Merge pull request #75 from planctechnologies/dev

Instance id descriptions