title: How to pass keyfile as argument in Rails project
body: <p>I'm using <a href="https://github.com/abronte/BigQuery/" rel="nofollow">the bigQuery gem</a> in my project. I initialize it with options client_id, service_email, key, project_id, and dataset. I have my .p12 file from Google that I want to pass in but I'm not sure where to put the file in my Rails project - I tried putting it in the same directory as my config file and passing the relative path name, but I'm getting an invalid passphrase error. Specifically, <a href="https://github.com/abronte/BigQuery/blob/master/lib/bigquery.rb" rel="nofollow">line 10</a> is throwing an error when load_key is being called:</p>
  
  <pre><code>key = Google::APIClient::PKCS12.load_key(
    opts['key'],
    "notasecret"
  )
  </code></pre>
  
  <p>So clearly it's not loading the key file correctly. I'm terrible at Rails asset control - where should I put my keyfile and what pathname should I pass in my options hash?</p>