Revert "Travis: don't try to test on Rails 3"

This reverts commit 4305c5559a025794df408a9bc31264e79e0469a6.
Revert "Travis: no need to exclude Rails 3 + Rails 2.0.0"

This reverts commit f952752aa9a930df821feba34be9e42827073b36.
Revert "Remove Rails 3 support"

This reverts commit 03f4f0e8efa93d3d635b7b542f14afc7b716060c.
remove requires to go back to autoloading and avoid dependency issues on rails 3
Merge pull request #47 from grosser/r30

Fix rails 3.0 errors