job file: append to status file.
Merge branch 'master' into job-status
Populate runtime DB with job submit method ID.

Only at, background and loadleveler at the moment.
Merge branch 'master' into job-status
job status file: add PID.
Create task job log dir in the submit command.

Since moving task log dir config to the site/user file, the "cylc
submit" command (and "cylc jobscript", which wraps it) failed if
the task job log dir did not already exist.
Merge pull request #282 from matthewrmshin/job-status

Job status
Merge pull request #285 from hjoliver/274-create-task-log-dir

Create task job log dir in the submit command.