Add support for python workers

[robertmaynard]

We need the ability to generate a python interface to the worker class.

This would allow remus users to develop workers in python, and hook them up to a c++ application that is submitting the jobs.

I want the python code to look something like the following:

from remus.common import MeshIOType
from remus.meshtypes import Model, Mesh3D
from remus.worker import ServerConnection, Worker, Job
from remus.proto import JobRequirements, JobSubmission, JobContent, JobProgress ,JobStatus, JobResult

conn = ServerConnection()
in_out_type = MeshIOType(Model(),Mesh3D())
w = Worker( JobRequirements( in_out_type, "ExampleWorker", ""), conn)

j = w.getJob()
content = j.details("data")

message = "hello from a python worker"
status = JobStatus(j.id, JobProgress(message) )
w.updateStatus( status )

status.progress = JobProgress(message, 50 )
w.updateStatus(status)

result = JobResult(j.id, "Python worker is now finished")
w.returnMeshResults(result)