Conflicted dependencies with Rails 4

Bundler message:


```
Bundler could not find compatible versions for gem "activerecord":
  In Gemfile:
    sequenced (>= 1.3.0) ruby depends on
      activerecord (~> 3.0) ruby

    rails (= 4.0.0.rc2) ruby depends on
      activerecord (4.0.0.rc2)
```