Add flag make_response

Now render_to_pdf can return a HttpResponse or a string with a file path.

Will return an HttpResponse (with file attached)

response = render_to_pdf(request, 'frula')

Will return a string with a file path.

file_path = render_to_pdf(request, 'frula', make_response=False)

Release v0.2

Fixed some bugs.

Release v0.1

Initial Release.