Better support for streaming data in multi-fs.

Added handling for readable streams in the SSH client.
Switched the manta client to always use write streams under the hood.
Added a test that exercises the streaming input case.
Fixed various problems revealed by jshint.
Deduplicated requires in a couple of spots.
Resolve that path!
Add a task queue to multi-fs stolen from the one in cuttlefish.
Concurrency defaults to 1 at the moment; this should be configurable.
Whitespace & a function name tweaked.
Nuke the lingering unnecessary call to _done().
Merge pull request #1 from npm/more-streams

Better support for streaming data in multi-fs.