URI and multiple-output support

[richardotis]

This is a feature request which is probably out of scope for #28.

Can every place where the run settings file accepts a filename or path, accept a general URI (e.g., https, ssh, git)? I think urlparse/urllib in the stdlib makes this a reasonable request.
See: https://stackoverflow.com/questions/22238090/validating-urls-in-python
One complicating factor is all the calls to open() and np.load() would need to get filtered through urllib, but I think this would be a very nice feature long term: Download datasets pinned to a Git repo, upload output TDBs to an S3 bucket, etc.

Related to this, being able to specify the output key multiple times would be useful once it would be possible to write results out to multiple remote locations.