repo builds: add support for creating qbsp

create_installer.py (and friends) should support creation of a QBSP file out of an online repository. QBSP file is essentially an online repository that is archived with 7z and has .qbsp extension, which can then be easily delivered to users.

Some configuration option should be made available that tells the scripts that the repo created from the repo configs should be 7z'ed and scp'd to some configured location.