Ability to pass additional arguments to getlocal.

http://www.ruby-doc.org/core-2.1.3/Time.html#method-i-getlocal accepts additional arguments to get Time object in particular time zone you want like this:
Time.now.getlocal(14400) # My current timezone is Moscow +0400
This commit allows this for ActiveSupport::TimeWithZone objects so from now on you can do this:
Time.current.getlocal(14400) # 2014-09-23 12:53:05 +0400
Time.zone.now.getlocal(14400) # 2014-09-23 12:53:05 +0400