Merge pull request #76 from aspiers/default-to-version-4

change default to SUSE Cloud 4
fix usage text

120e99d3dd broke the usage text since default variables need to be set
prior to calling parse_opts() which calls usage().
extract zypper_addrepo() and zypper_set_priority() functions
remove Devel_Cloud_Shared_11-SP3_Update

This was omitted from setup_zypper_repos() when originally introduced.
automatically trust GPG keys for new repos
fix cloud_admin pattern installation check

zypper -n patterns lists all patterns by default, so I'm
not sure how this check ever worked before.
do validation on cloud version number
Cloud 4 and all subsequent versions will support HA

(probably, it's a safer default for now anyway ...)