update therubyracer to 0.11.3
use Time.current instead of Time.now and Time.zone.parse instead of Time.parse

building out full time zone support (like what we did with Date.today -> Date.current in dd8884b)
we must move to using Rails 3-2-stable instead of 3.2.11 because of rails/rails@d39d878 not being included in a released version of 3.2.x