added django 1.7 to .travis.yml
added django 1.7 to .travis.yml

Stranger6667/django-hstore,Stranger6667/django-hstore,djangonauts/django-hstore,Stranger6667/django-hstore,pombredanne/django-hstore,djangonauts/django-hstore,pombredanne/django-hstore,djangonauts/django-hstore,djangonauts/django-hstore,pombredanne/django-hstore,pombredanne/django-hstore,Stranger6667/django-hstore