Add small amount of additional flexibility.

flags support are more flexible - here using flagset for remainder of <cmd> in run only.
(other commands could benefit with this approach). Should ensure temporary backward compatibility also.
Startup jb now emits a 'signature' string. Please change/adapt version etc as needed.
This will become important as large/(potentially)breaking changes are filtered in, and expecially for those interested in just using 'binary' packages (for quick troubleshooting).
Jeebus now emits its http 'server' data onto the bus. This is important so that remote connections to the bus can derive the endpoint of the 'server'. For example, I'll patch hm shortly a small tweak that allows us to remove the hard coded :3333, :3334, :3335 that creeps into coffescript and has me scratching my head for 30mins working out if I broke rpc :)
Also added SIG for jb run, only basic, so we remember its there to do 'more' later.
(helpful if you use such as upstart/deamon-ize etc).
Finally, jb serial will defer a detatch, but I plan on arguing for a slightly different approach anyhow.