Add runs using csh as shell

[FelipeLema]

There's an issue with addprocs when remote shell is `csh. Currently, this configuration is not being tested in buildbot runs.

If I understand correctly, if one were to run tests using a non-default remote shell, this repo is the place to do so.

@staticfloat

[DilumAluthge]

This is kind of tricky. I don't think we really have the resources to run the entire Base Julia test suite with multiple different shells.

If the issue is specifically with addprocs, perhaps we could add a few tests to the Distributed stdlib test suite that test the desired functionality. That would go in the JuliaLang/julia repository, since the Distributed stdlib currently lives inside the JuliaLang/julia repository.