Only show controllers matching white/blacklist (#416)
Only show controllers matching white/blacklist (#416)

In controllerpicker, only show existing controllers for a spell if they
match the white/blacklisted clouds for the spell.

If none match, skip the picker and go straight to the clouds view to
bootstrap a new controller on a valid cloud.

Fixes #413

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