I added omniauth gem to my gemfile and tried to run bundle install, but got a message about incompatibility of rails and bundler versions. I tried to update rails, but got messages about incompatibility with other gems. How can I downgrade bundler to 1.0? 

    $ bundle install
    Fetching gem metadata from http://rubygems.org/......
    Fetching gem metadata from http://rubygems.org/..
    Bundler could not find compatible versions for gem &quot;bundler&quot;:
      In Gemfile:
        rails (= 3.0.0) ruby depends on
          bundler (~&gt; 1.0.0) ruby

      Current Bundler version:
        bundler (1.1.1)

    This Gemfile requires a different version of Bundler.
    Perhaps you need to update Bundler by running `gem install bundler`?

and

    $ bundle update rails
    Fetching gem metadata from http://rubygems.org/......
    Fetching gem metadata from http://rubygems.org/..
    Bundler could not find compatible versions for gem &quot;bundler&quot;:
      In Gemfile:
        factory_girl_rails (&gt;= 0) ruby depends on
          bundler (~&gt; 1.0.0) ruby

      Current Bundler version:
        bundler (1.1.1)



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How to downgrade bundler or upgrade rails?