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

I've amended the sqla.py module  [ SQLAjqGridWidget._get_data() ] 
so that datetime.date objects (as well as datetime.datetime objs) are covered by 
the date -> string conversion (to circumvent the error caused by @jsonfiy in the `request`) 

see line 144:
  - if isinstance(data, datetime.datetime):
  + if isinstance(data, (datetime.datetime, datetime.date)):

... it'd be nice if the commit message didn't read:
"Resolved 'is not JSON serializable' error caused by [RobertSudwarts]" -- kinda looks like I did something horrendously wrong!!   :)