Fix deprecation warnings with ActiveSupport ~> 2.3.5

I've gotten tired of this message in my console. :)

    DEPRECATION WARNING: require "activesupport" is deprecated and will be removed in Rails 3. Use require "active_support" instead. (called from /vendor/bundle/ruby/1.8/gems/activesupport-2.3.11/lib/activesupport.rb:2)

I chose this approach instead of a nested begin/rescue block so that people using versions before 2.3.5 didn't have to suffer the overhead of two exception backtraces being generated. I tested with the first and last patch versions of each minor version of ActiveSupport between 2.0.0 and 3.0.5