[gem] Bump rails version to ~> 3.0.20
Generate new Rails boilerplate, update environments
Upgrade routes
Rails 3: RAILS_ENV => Rails.env
Rails 3: RAILS_ROOT => Rails.root
Rails 3: RAILS_DEFAULT_LOGGER => Rails.logger
Rails 3: Update AR finders to use .first and .all
Rails 3: named_scope => scope
Rails 3: Upgrade ActionMailer format
Rails 3: Move parameter filtering into application.rb
Rails 3: Update ERB block helpers
Rename the last two .rhtml views to .html.erb
Remove patches for CVE-2013-0156 and CVE-2013-0333

We're now running a rails version that includes these patches.
Rails 3: Update setting of date/time formats
[gem] Add memcache-client to gemfile
Rails 3: Fix routes, use strings for HTTP verbs
[gem] Upgrade acts-as-taggable-on
Remove new_rails_defaults initializer
Fix root path definition
Fix user_favorites routes