TODO

ensure environment cannot contain spaces
standardize indented logs & log_color/echo_color
list available environments when env is missing
check required commands on server (at setup)
add -e|--environment option to support environments named after a sub-command
setup and rev should update the git clone url if it changed
add -q|--quiet option (e.g. list releases)
add confirmation prompts
verbosity (simple commands, full commands)
command line options to add hooks (ensure they can be specified multiple times)
npm-like Scripts (also usable as hooks)
make configuration file optional
support a symlink for the configuration file
create a deployment log (include commit)
add commands to manipulate previous releases (print info, rollback)
add --path option to exec
more detailed errors if setup has not been done
make config & config-all command fail if key not found