Simplify creating a gateway from an envrionment

[m-g-k]

When creating a Gateway from an Environment, rather than always making the user type in a name, it would be useful if the extention suggested a default name of "[EnvName]_gw". For example, if I have an Envrionment called MyNet, suggesting MyNet_gw as a default gateway name would save the user some typing. Of course the user could override this and change the default name if required...