Adding extra `--once` flag to `tory-register`

to be more clear than `--loop-seconds=0`.
Adding some tests around the `--once` option
Merge pull request #41 from modcloth/add-once-option-for-register

Adding extra `--once` flag to `tory-register`
Switching from joyent payload primaryIp to ips.0

as the former only present in listmachines output and is not documented
as a return param anywhere :scream_cat:.
Merge pull request #45 from modcloth/switch-from-primaryip-to-ips-0

Switching from joyent payload primaryIp to ips.0
Merge remote-tracking branch 'origin/master' into minor-changes

Conflicts:
	bin/tory-sync-from-joyent