rename addon-remove to addon-destroy
Add pg-list command for tree list of pg databases
add pg-unfollow command
Fix login issues with no netrc file

Fixes #110.
remove color from confirmation prompt.

Fixes #112.
Show `hk help commands` in help output.

Fixes #107.
fix IsStarterPlan() for devcloud plan
postgres standalone is now a bool everywhere
fix postgresql db deserialization tests
report panics to Rollbar unless version is dev
pg info service_port is now an int
login command no longer takes email as an arg

Email is requested at a prompt. This allows us to suggest the previous
email address from the netrc as an option rather than always requiring
the user to enter it, even if they've already done so on a previous
login attempt.

Fixes #109.
better help for create
a skeleton for zsh completion with app name suggestions
cache region names for 2 weeks
don't use completion caches in a non-default cloud
organize and add all commands which only require app flag
add app flag handling for some other commands as placeholders
remove -s option for _arguments, explain other options
zsh completion of addon services and plans