fix. error importing UserMetricError, use base Exception class.
mod. use http://noc.wikimedia.org/conf/ dblists to build project : db map.
fix. don't need to check concurrent jobs to add to wait queue.
fix. When project as a function of cohort tag  from url is invalid use whatever is passed in the request.
fix. ensure that user IDs are strings so they can be matched.
Merge pull request #21 from rfaulkner/working

Fixes for WEP_AR to build cohort composites and other misc
mod. add docs / pep8.
fix. ref to "<table>" rather than "<database>" in unformatted query.
Merge branch 'working'
mod. In requests_notification_callback renamed cache to job_list for clarity.
mod. move lock defintion to api package namespace and rename.
add. req_cb_flag_job_complete to handle setting job status to complete.
add. REQUEST_PATH constant.
fix. get_url_from_keys, parsing url path.
mod. move addition of job to job queue from view to when job is actually added to wait list in job_control.
Merge branch 'working'