JRuby testing, remove 1.8.7 from tests (unsupported), fix some tests

Begin my help (https://twitter.com/leopard_me/status/358363747850526721) for redis-store :)

This commit contain:
 - remove 1.8.7 support and testing
 - fix tests for Rails 3.2
 - added jruby testing
 - Begin fixing tests for Rails 4 (wok not finished)