Mongoengine taskstatus

This contains -

1. Schema definition for TaskStatus inherited from mongoengine.Document
2. Added fields.py to define custom fields used in pulp that are not available from mongoengine.
3. Updated save method on TaskStatus to do the validation of fields as well as upserts.
4. Updated task status manager with mongoengine queries
5. Added and updated unit tests in various files as appropriate.
6. Enabled a bunch of unit tests in test_dispatch.py which were not running because of wrong test names.

Since there are a lot of in-place changes, pull request diff looks confusing at some places. It is better to look at the whole file instead of the diff. 
On 12/05/2014 02:25 PM, bmbouter wrote:
> In server/pulp/server/async/task_status_manager.py:

In the spirit of deletion, there is probably no reason for this entire
module to exist anymore. All code should live on the model, or on the
MongoEngine provided manager that comes with the model. Most of the code
in this module is just reimplementing things we get for free from
MongoEngine.