change login check (#206)
change login check (#206)

Checking available() mostly served to check that there was a current
model. Let's just do that directly.

Also move check after controller check to get the right error message if
you don't have a controller.

Finally, a rename of environment, to address part of #202

Signed-off-by: Michael McCracken <678f76d0129c6a47299e3c6abb92ed26d253a960@canonical.com>
battlemidget/conjure-up,ubuntu/conjure-up,ubuntu/conjure-up,Ubuntu-Solutions-Engineering/conjure,battlemidget/conjure-up,Ubuntu-Solutions-Engineering/conjure,conjure-up/conjure-up,conjure-up/conjure-up