Different behavior for BigDecimal#floor in Ruby 1.8 and Ruby 1.9

Ruby 1.8 (supplied by Rails' ActiveSupport)

>> BigDecimal.new("0.1").floor.class
=> BigDecimal

Ruby 1.9 (supplied by Ruby 1.9 itself)

>> BigDecimal.new("0.1").floor.class
=> Fixnum

In fact, Float#floor has changed from Ruby1.8 Show archive.org snapshot to Ruby 1.9 Show archive.org snapshot which is used by BigDecimal#floor internally.

Attached initializer backports Ruby 1.9 behavior to Ruby 1.8.