Loosen Django version requirement spec
Loosen Django version requirement spec

PR #188 exposed a Django version requirement in the travis spec that was
too tight. By converting from an inclusive ordered matching specifier to
the compatibility specifier, we ensure that e.g. Django 1.8.1 (or
whatever is current) will be used to fulfill a Django 1.8 dependency.

Ref: https://www.python.org/dev/peps/pep-0440/#compatible-release
Signed-off-by: martin f. krafft <acc3492a66a5949176a2fc8886cf441478ca46a1@madduck.net>

CTPUG/wafer,CTPUG/wafer,CTPUG/wafer,CTPUG/wafer