Add port option to specify the starting port for processes

Fixed a few bugs, nothing to specific

Changed env format to map[string]string from []string, allowing faster
discovery. Included helper functions for converting between the two
since exec.Cmd.Env takes []string

The *Process.Exec now properly handles the number of processes to run
and it's port. Still undecided what else I'll need to do to make it look
properly though.
Add unknown option the the command statements