Merge pull request #2 from felafelwaffle/master

Several minor documentation fixes
handle new activerecord postgres result set class for rails v3 and higher
Merge pull request #3 from felafelwaffle/felafelwaffle-add-support-for-posgres-on-rails-3-plus

handle new activerecord postgres result set class for rails v3 and higher
better gemspec
cache keys/values are sorted (with configurable sort keys)