Use python's json rather than Django's

django.utils.simplejson is deprecated; Python 2.6+ includes json.
removing to resolve conflict

Conflicts:
	components/tools/OmeroWeb/omeroweb/webgateway/views.py
Merge remote-tracking branch 'origin/develop' into simplejson_upgrade

Conflicts:
	components/tools/OmeroWeb/omeroweb/webgateway/views.py
Merge pull request #1886 from joshmoore/simplejson_upgrade

Use python's json rather than Django's