ci with appraisal against rails2.3, rails3

- Use appraisal for multi-gemfiles test
    - https://github.com/thoughtbot/appraisal
    - https://rubygems.org/gems/appraisal
- Use generated gemfile by appraisal in travis-ci
- Ignore generated gemfile.lock by appraisal
- Install tokyo-cabinet in travis-ci
- Adjust sqlite3 for jruby
- allow failure against rails2.3, rails3
    - fix step by step :cat: