Adding func to remove old job from queue

- Recreate migration step for adding group model.
- Assign job foreignkey to group as None
Added test for new api
Merge branch 'release/1'
Added condition for filter in job must be executed

- Added more test for api
- Removed assigning default value for group in job foreignkey.
- Added migration folder in packages list.
Added more test for api

- Cleaned unneed comments.
Change async version
- Removed first expectation ( of cannot run migrate to add job foreignkey to group because job model did not assign default=None, actually it does not related.) default=None from field group foreignkey of job model.
- Created new 2nd migration for async for make sure that come from actual model.
- Cleaned out unneed code
Added newline of file
Cancelled representing Q obj in vars

- because travis report error
Followed travis warning
Merge branch 'master' of github.com:vernomcrp/django-async into feature/remove-old-jobs
Add a function that can be placed into the async queue for clearing out old jobs.
Fix up layout.
Remove commented code.
Fix up English in description.
Various small fixes to `remove_old_jobs`

* Don't hard code the 8 hours retry time.
* Use a normal default for the 30 days.
* Remove a local function that isn't doing anything.
Fix description of what this feature does.
Removed some broken group logic that wasn't doing anything.