Include ROA headers on GET (.save_base) and DELETE (.delete)

+ Also set 'format' GET arg using mapped argument name
Update doc
Merge branch 'jathanism-send_headers' into develop
Update version number
Make Django ROA run under Django 1.7
Make Django ROA run with Python 2.6
Plug Travis to this repository (#7)
Make Django ROA run under Django 1.4