Set IN_FORM_CONTEXT_VAR as part of extra_context.

Fixes #73.
Added test case.
Making test suite run again with Django 1.6. A reason was django-discover-runner, which exits if Django >= 1.6 is detected.
Fixes #83 -- Fixing floppyforms to work with current Django master (1.6.x). There was a semantic change in the widgets NumberInput.__init__ method. It's logic is now adopted in floppyforms.
Adding current django master as tested environment to tox.ini
Getting rid of deprecation warnings introduced by Django >= 1.6
Fixed #82 -- Removing _has_changed method from widgets for Django >= 1.6
Updating tox file to include tests for Django 1.6.
Adding tests for Django 1.6 to Travis CI builds.
Work around a parse error in Django 1.4 for recent GEOS versions
Fix some flake8 violations
Simplified tox/travis setup
Merge branch 'master' of github.com:brutasse/django-floppyforms

Conflicts:
	.travis.yml
	tox.ini
Add universal wheel support
Ignore build, fix docs date
Bump to 1.1.1
return ctx was missing from one of the examples
Merge pull request #92 from kefirbandi/return_ctx

return ctx was missing from one of the examples
Allow override of template_name in __init__() and render().
Ensure that a template_name 'override' of `None` doesn't override.

This is important for cases where e.g. widget.render() might be wrapped by
another function that accepts a `template_name=None` optional argument; it's
nice if the wrapper function can just pass that on directly rather than having
to check for `None`.