Checking the status of remote workflows.

[BoPeng]

Remote workflow is getting easier with #1407 and #1418

Currently sos run -r simply execute the workflow on the remote host, or submit it to remote cluster system. There is no way to check the status of the workflow or get the error message.

It is tempting to pipe the output from the workflow to the local host, and allow the use of sos status to check the status of the remote workflow. Not sure how exactly we should do that.

[BoPeng]

So what we need to have are:

1. Add an option, perhaps -m for monitor, to start a monitoring thread, similar to the task monitoring process.
2. Encourage users to specify workflow err and out files in the right place so that sos status -v4 can pick up.
3. Add workflow monitoring to command sos status.
4. Add support for sos kill, sos purge etc
5. Automatically add option -m when sos run -r host to sos run on remote host.

[bioworkflows]

all done. (It is supposed to be Christmas time. :-( )