title: BeautifulSoup does not parse xml with other encoding than utf-8
body: <p>I can read all xmls files that starts with <code>&lt;?xml version="1.0" encoding="utf-8"?&gt;</code> but I can not read the files starts with <code>&lt;?xml version="1.0" encoding="ISO-8859-1"?&gt;</code>.</p>
  
  <p>Specifically, I have two files:</p>
  
  <p><strong>xml_iso.xml</strong>:</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="ISO-8859-1"?&gt;
  &lt;note&gt;
      &lt;to&gt;Tove&lt;/to&gt;
      &lt;from&gt;Jani&lt;/from&gt;
      &lt;heading&gt;Reminder&lt;/heading&gt;
  &lt;/note&gt;
  </code></pre>
  
  <p><strong>xml-utf.xml</strong>:</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
  &lt;note&gt;
      &lt;to&gt;Tove&lt;/to&gt;
      &lt;from&gt;Jani&lt;/from&gt;
      &lt;heading&gt;Reminder&lt;/heading&gt;
  &lt;/note&gt;
  </code></pre>
  
  <p>With the following code I can find the <code>note</code> for the file with <code>utf-8</code> but I can not find it in the file with the other encoding. How can I solve that?</p>
  
  <p>Example code:</p>
  
  <pre><code>import unittest
  
  from bs4 import BeautifulSoup as Soup
  
  class TestEncoding(unittest.TestCase):
      def test_iso(self):
          with open('tests/xml-iso.xml', 'r') as f_in:
              xml_soup = Soup(f_in.read(), 'xml')
          print('xml-iso:\n{}'.format(xml_soup))
          note = xml_soup.find('note')
          self.assertIsNotNone(note)
  
      def test_utf8(self):
          with open('tests/xml-utf.xml', 'r') as f_in:
              xml_soup = Soup(f_in.read(), 'xml')
          print('xml-utf8:\n{}'.format(xml_soup))
          note = xml_soup.find('note')
          self.assertIsNotNone(note)
  
  if __name__ == '__main__':
      unittest.main()
  </code></pre>
  
  <p>Versions:</p>
  
  <ul>
  <li><p>Python 3.5.2</p></li>
  <li><p>beautifulsoup4==4.6.0</p></li>
  </ul>