Make cobbler_web work with mod_nss

For unknown reasons, cobbler_web will sometimes crash when run under
mod_nss, with the failure declared as
" Settings' object has no attribute 'ROOT_URLCONF'"
(This problem is not observed using mod_ssl).

ROOT_URLCONF is explicitly declared in settings, so apparently the
wsgi process is not always importing the correct settings file.

Fix this by inserting cobbler_web's dirs at the beginning of the path.
cobbler.spec - don't require mod_ssl

cobbler will work with mod_nss or mod_ssl, so mod_ssl is not a
requirement.

Furthermore, redhat ipa uses mod_nss, installing mod_ssl
conflicts. So, be nice. Users of cobbler should have no trouble
installing a package themselves :^).
Merge pull request #573 from mark987/issue572

Issue572 - make cobbler web work with mod_nss