Support rails4
Use string instead of symbpl for css name

Symbol value is treated as proc using `Proc#to_proc`.
Add 'active_support/core_ext/proc'
rspec-rails does not depend on rspec anymore
Use released version of 3.2 as minimum
Add appraisal for Rails 4
Fix Travis CI support again; add Rails 4
Update README and Changelog.md
Eliminate deprecation warnings in Rails 4
Don't CI Rails 4 + MRI 1.8.7
fixup! Add appraisal for Rails 4
Clean up code
Merge branch 'rails-4'