Adjust Django versions, lint against 1.6 as we do not support 1.7 yet

Signed-off-by: Michal Čihař <michal@cihar.com>
Run Selenium tests against MySQL

Signed-off-by: Michal Čihař <michal@cihar.com>

Conflicts:
	.travis.yml
Merge branch 'master' into bootstrap

Signed-off-by: Michal Čihař <michal@cihar.com>

Conflicts:
	.travis.yml