Time.zone utc offset not freezing correctly

[epbarger]

Within an RSpec test...

  Timecop.travel(Time.parse('June 2014'))
  Time.use_zone(customer.time_zone) do
    customer.time_zone # => "Pacific Time (US & Canada)"
    Date.today # => Sun, 01 Jun 2014
    Date.today.in_time_zone.utc_offset # => -25200 (correct for the frozen Date)
    Time.zone.utc_offset # => -28800 (incorrect for frozen Date, correct for current Feb 9)

    example.run
  end
  Timecop.return

[yaauie]

probably pretty closely-related to #130 and #134, but also very tightly-coupled with ActiveSupport (since Date#in_time_zone, Time#zone, ActiveSupport::TimeZone#utc_offset all need to correctly be aware the mocked time instead of real time), and may be dependent on what version of ActiveSupport you're using.