title: Can't complete upgrade to Rails 5 because of SSL certificate
body: <p>I've been at this upgrade for multiple hours now and am finally truly stuck.
  It all started when I received the typical <code>Bundler::Fetcher::CertificateFailureError</code>.  After much tinkering I think I have everything upgraded to the most current version</p>
  
  <pre><code>$ gem -v
  2.6.9
  
  $ ruby -v
  ruby 2.3.3p222 (2016-11-21 revision 56859) [i386-mingw32]
  
  $ bundle -v
  Bundler version 1.14.2
  </code></pre>
  
  <p>At some point I changed my gem source with </p>
  
  <pre><code>$ gem sources --remove http://rubygems.org
  $ gem sources --add http://rubygems.org
  </code></pre>
  
  <p>I've also changed my Gemfile to http</p>
  
  <p>When I run `bundle install' I get the following error (note, I had to manually break the bit.ly url to post the content of the error)</p>
  
  <pre><code>Fetching source index from https://rails-assets.org/
  
  Retrying fetcher due to error (2/4): Bundler::Fetcher::CertificateFailureError Could not verify the SSL certificate for https://rails-assets.org/.
  There is a chance you are experiencing a man-in-the-middle attack, but most likely your system doesn't have the CA certificates needed for verification. For information about OpenSSL certificates, see http://bit. ly/ruby-ssl. To connect without using SSL, edit your Gemfile sources and change 'https' to 'http'.
  Retrying fetcher due to error (3/4): Bundler::Fetcher::CertificateFailureError Could not verify the SSL certificate for https://rails-assets.org/.
  There is a chance you are experiencing a man-in-the-middle attack, but most likely your system doesn't have the CA certificates needed for verification. For information about OpenSSL certificates, see http://bit. ly/ruby-ssl. To connect without using SSL, edit your Gemfile sources and change 'https' to 'http'.
  Retrying fetcher due to error (4/4): Bundler::Fetcher::CertificateFailureError Could not verify the SSL certificate for https://rails-assets.org/.
  There is a chance you are experiencing a man-in-the-middle attack, but most likely your system doesn't have the CA certificates needed for verification. For information about OpenSSL certificates, see http://bit. ly/ruby-ssl. To connect without using SSL, edit your Gemfile sources and change 'https' to 'http'.
  Could not verify the SSL certificate for https://rails-assets.org/.
  There is a chance you are experiencing a man-in-the-middle attack, but most
  likely your system doesn't have the CA certificates needed for verification. For
  information about OpenSSL certificates, see http://bit. ly/ruby-ssl. To connect
  without using SSL, edit your Gemfile sources and change 'https' to 'http'.
  enter code here
  </code></pre>
  
  <p>So I'm right back where I started from.  On a side note, I'm now getting another error when I try to https: to my <code>gem sources</code> but that might be better as a different question after I get this one taken care of.</p>