Update travis ci to support testing against the latest stable versions of django 1.5, 1.6 and 1.7.
Update travis ci to support testing against the latest stable versions of django 1.5, 1.6 and 1.7.

Signed-off-by: David Black <c4b737561a711e07c31fd1e1811f33a5d770e31c@atlassian.com>

dbaxa/django_xss_detection,dbaxa/django_xss_detection