Implement Job class

[bschroeter]

As per other implementations, it may be useful to have a discrete Job class that is returned on submission that abstracts back to the client object in order to check statuses etc. This way the user does not need to maintain a list of job ids, rather, the Job object will have the ID as an attribute.

Consider the following example:

# Submit a job, get a Job object
job = client.submit("job.sh")

# Get the JOB id.
print(job.id)

# Check the status
status = job.status()

# Hold, release, cancel etc.
job.hold()
job.release()
job.delete()

Within the job class there can also be links to any native objects or attributes that are specific to the scheduler, as well as those which are generic across the board.

Just a thought starter, but things are heading down this path...