In asset_tag_helper_test.rb there is an assert on the number of bytes in a
concatenated file. This test failed because Windows converts \n to \r\n as
the default for "w". This is different than in *nix systems where there is
no conversion done.
THe test that failed was test_caching_stylesheet_link_tag_when_caching_on
Using bin mode fixes this behavior on windows and makes no change on the