Resolved 'is not JSON serializable' error caused by
use of datetime.date() objects in sqalchemy model.

  modified:   tw2/jqplugins/jqgrid/widgets/sqla.py

see line 144:
  - if isinstance(data, datetime.datetime):
  - if isinstance(data, (datetime.datetime, datetime.date)):
Merge pull request #9 from RobertSudwarts/develop

Resolved 'is not JSON serializable' error for datetime.date objects