Prepare to 4.0.2
Make possible to use sprockets-rails 2.1
Prepare to 4.0.3
Change the minimum version requirement

Closes #262
Allow to use any sprockets version in the 2.11 series
Prepare for the 4.0.4 release
Test with 4-0-stable and 4-1-stable
test_files is deprecated in gemspec
Use expanded even in production