Implement static_live_server (Django1.7)

fixes #120

<strike>WIP, not ready for merging
Documentation still need to be addressed</strike>
Hmm. Just changing this without any documentation/note in the release notes is not very nice and might break things for people that rely on this name.

I think we should switch to DJANGO_LIVE_TEST_SERVER_ADDRESS but fallback to the old one and issue a deprecation warning if the old name is used.