Updated documentation

* added RVM option for single-user install
* clarified Web Server options
* bluepill sample config: create socket directory if it doesn't exist
* add multisite.yml.production-sample
* rename production.sample.rb (OCD)
* make two database.yml samples (one for dev, one for prod)
* fixed travis build (database.yml.sample renamed)
* fix other references to database.yml.sample
* clean up 'rvm requirements' instructions as per @mpapis