Bring back CLEAN_EXPIRED_ASSETS environment variable.

This allows the clean expired task to be run at the same time as precompiling,
which can save the overhead time of having to execute another rake task.
Support Ruby 2.x
Merge pull request #98 from ministrycentered/ruby2

Support Ruby 2.x
bump versions
Merge pull request #60 from GUI/master

Bring back CLEAN_EXPIRED_ASSETS environment variable
bump version
Revert "Bring back CLEAN_EXPIRED_ASSETS environment variable."

This reverts commit 668f13b55dcf03e1dd083acf5afa54ea754bf85b.
bump
Merge branch 'master' of https://github.com/ndbroadbent/turbo-sprockets-rails3