Issues/50 from ical, cleaned up

Cleanup of #226.

Squashed all commits into one, removed non-ical changes, unbroke tests, and committed. Sorry to have lost all the contributors, but it was too unwieldy to rebase. Credits to @skyporter @jgauby @btucker @spra85.

I hope this helps in getting iCal parsing finally merged.
Good idea. I can't find it in [Ruby doc](http://www.ruby-doc.org/core/Time.html) nor [Rails](http://api.rubyonrails.org/classes/Time.html), but [apidock](http://apidock.com/ruby/Time/parse/class) shows it being present in 1.9 as well. But they're there, and with this change the ical specs still work for both Ruby 1.9.3 and 2.1.3 as well as ActiveSupport 4.1.8, 4.0.12, 3.0.20 and 3.1.12.