Missing routes for Remote-Remote

[mrocklin]

We lack direct routes to copy data between remote computers without touching the local system.

into('ssh://A:myfile.csv', 'ssh://A:myfile2.csv')  # Should be a remote local copy
into('ssh://A:myfile.csv', 'ssh://B:myfile.csv')  # Should result in a remote call to scp
into('hdfs://A:myfile.csv', 'ssh://A.myfile.csv')  # Should result in hadoop fs calls
into('ssh://A:myfile.csv', 'hdfs://A.myfile.csv')  # Should result in hadoop fs calls
...

When interacting with AWS the inter-node bandwidth is very high. It'd be nice to leverage this instead of pulling down and pushing up from local.

[mrocklin]

One tricky thing is that we'll probably have to pass credentials up securely.