Stop and restart multiple processes by pid or name

Multi stop:
`bs stop 1111 2222 3333`
Multi restart:
`bs restart 1111 2222 3333`
Stop all:
`bs stop all`
Restart all:
`bs restart all`

fixes #18 
If I've got a bunch of processes, and I only have access to some of them, but I do `bs restart all`, doesn't this mean I'll see a stack trace for the last process that I couldn't restart?

It might be better to check the error code for `EACCES` and print a warning that the user doesn't have permission to restart that particular process and only throw if a non-EACCES error occurs.

What do you think?