Fix several issues for Django 1.6
Adjust version dependencies for Django 1.6
Disable template timings toolbar panel
Add migration for NullBoolean field
Offer wizard works with JSON session serializer
Add note to release doc on Django 1.6 support
Merge pull request #916

Conflicts:
	.travis.yml
	requirements.txt
	tox.ini
Remove unnec. templates

Now superceded by changes in master.
Modernise requirements files

Bring package version up to date.