title: gem conflict oa-oauth and fb_graph on the multi_json gem
body: <p>how do i solve this kind of conflict?</p>
  
  <pre><code>Bundler could not find compatible versions for gem "multi_json":
    In Gemfile:
      fb_graph (= 2.6.2) ruby depends on
        multi_json (&gt;= 1.3) ruby
  
      oa-oauth (= 0.3.2) ruby depends on
        multi_json (1.0.4)
  </code></pre>
  
  <p>my gem file:</p>
  
  <pre><code># oauth authentication
  gem 'oa-oauth', '0.3.2', :require =&gt; 'omniauth/oauth'
  gem 'oa-openid', '0.3.2'
  gem 'fb_graph', '2.6.2'
  gem 'twitter', '4.4.4'
  gem "koala", '1.6.0'
  </code></pre>
  
  <p>thanks</p>