* Default to using the auth.curoverse.com SSO server. Add instructions

* Default to using the auth.curoverse.com SSO server. Add instructions
in config.yml.example for using a local SSO server.

* Do not prepopulate the config.yml file generated by build.sh with
random values for _PW and _SECRET variables, let config.rb deal with
that at build time.

* Make config.rb a bit more robust in choosing those values for _PW and
_SECRET by not depending on any particular key order in the config Hash.

refs #3363