Merge pull request
#1634 from minrk/proxylauncher...
Merge pull request
#1634 from minrk/proxylauncher
Incremental improvements to SSH launchers:
* add to_send/fetch steps for moving connection files around.
* add SSHProxyEngineSetLauncher, for invoking to `ipcluster engines` on a remote host. This can be used to start a set of engines via PBS/SGE/MPI *remotely*.
This makes the SSHLauncher usable on machines without shared filesystems.
When sending files, the destination directory must *already exist* - that is, `ipython profile create` may be necessary on the remote system, before the security dir exists for putting the connection file the first time.
