Add CentOSPlus repository for postfix dependency

Due to some sort of updated dependency during the PHP installation, postfix creates a failure in the entire chain over a missing libmysql package. By using the CentOSPlus repository, we're able to work around this.
Provide a redirect for any www subdomain requests

This adds our www redirect to the default nginx configuration so that we don't need to remember it each time.
Merge pull request #75 from washingtonstateuniversity/prod-fix

[PR] Resolve postfix dependency, add www subdomains