utility methods for shutting down cloud servers
remove nodes when removing instances
remove devices when removing instances
do nothing if server is None
Merge pull request #48 from planctechnologies/gns-133

Gns 133 Deleting an instance orphans devices on canvas
Grammar fixes
Merge branch 'dev' of github.com:planctechnologies/gns3-gui into dev
Fixes SecureCRT command line.
Merge remote-tracking branch 'origin/master'
IOSv and IOSv-L2 integration.
Merge remote-tracking branch 'origin/master'
Merge pull request #157.
Rename IOSv symbols + improve support for ASA on Windows.
Support for CPU throttling and process priority for Qemu.
Bump version to 1.2.1.dev2
Use bundled Qemu on Windows and OSX by default and checks if remote server are registered.
Fixes missing options.
Bump version to 1.2.1
Disable cloud.
Bump version to 1.2.2.dev1