title: Heroku rake db:migrate doesnt work
body: <p>im having this issue when i try to deploy my ruby on rails application to heroku, i check different posts here, because i saw this issue before but i couldnt fix it.
  when i try to run: </p>
  
  <pre><code>$ heroku rake db:migrate
  </code></pre>
  
  <p>I get a lot of these ones: <code>DEPRECATION WARNING</code>:</p>
  
  <p>and then:</p>
  
  <pre><code>rake aborted!
  Please install the postgresql adapter: `gem install activerecord-postgresql-adapter` (pg is not part of the bundle. Add it to Gemfile.)
  
  Tasks: TOP =&gt; db:migrate =&gt; db:load_config
  (See full trace by running task with --trace)
  </code></pre>
  
  <p>I tried to change my Gemfile with 'pg' and my group :assets do to :production, i know im missing something but i could'nt figured out what.</p>
  
  <p>Some ideas? </p>
  
  <p>Also when I go to the app url, I get this: </p>
  
  <pre><code>Application Error
  An error occurred in the application and your page could not be served. Please try again in a few moments.
  If you are the application owner, check your logs for details.
  </code></pre>
  
  <p>Thanks in advance for any suggest and help!!!</p>