Fix `UnboundLocalError` when no previous auto-scale groups
move all imports to the top
use boto to create load balancer

Was using the aws-cli since `create_load_balancer` would throw:

    TypeError: create_load_balancer() takes at least 3 arguments (5
given)

Turns out you have to pass `zones=None` explicitly if you provide a
list of subnet.

╯°□°）╯︵ ┻━┻
Turn on connection draining for created load balancers

Closes Issue #8