run: allow passing multiple job names as positional arguments to run command

To allow more easily start multiple jobs with same parameters, allow passing
multiple job names to run command as last positional arguments.
Merge remote-tracking branch 'peekeri/multi_run'

https://github.com/ohmu/tjob/pull/6

NOTE: This should be amended with the `required` flag if/when
https://github.com/jessevdk/go-flags/pull/122 is merged.