Support static or dhcp bridge configuration
Skip db initialization if it's there already
Use SELinux permissive instead of disabled

Usually a good idea to leave the system in permissive
so that we can at least gather information about
policy violations.
Package installation changes

* Use the eucalyptus-cloud-controller group
* Added missing unzip and ntp packages
* Use RPM with URLs to simply repo package install.
  No, this is *not* ideal, but makes the most sense in this case. Doing
  a yum install from a URL will return an error if the package is
  already installed, and we don't want that. There is also a check now
  to determine if the repo packages need to be installed.
* Moved repository urls into group_vars/all to keep things DRY
Skip creds tasks if they are already complete
Add checks to service registrations

Only register services if it hasn't been done yet.
Merge pull request #2 from mspaulding06/minor_changes

Changes I needed to build my cloud