title: python error on barcode generation
body: <p>I am using python 2.7 and pyBarcode 0.7 in Windows and I am trying to generate barcode as png image by using following sample code (available in pyBarcode webpage)</p>
  
  <pre><code>&gt;&gt;&gt; import barcode
  &gt;&gt;&gt; barcode.PROVIDED_BARCODES
  [u'code39', u'ean', u'ean13', u'ean8', u'gs1', u'gtin', u'isbn', u'isbn10',
   u'isbn13', u'issn', u'jan', u'pzn', u'upc', u'upca']
  &gt;&gt;&gt; EAN = barcode.get_barcode_class('ean13')
  &gt;&gt;&gt; EAN
  &lt;class 'barcode.ean.EuropeanArticleNumber13'&gt;
  &gt;&gt;&gt; ean = EAN(u'5901234123457')
  &gt;&gt;&gt; ean
  &lt;barcode.ean.EuropeanArticleNumber13 object at 0x00BE98F0&gt;
  # Example with PNG
  &gt;&gt;&gt; from barcode.writer import ImageWriter
  &gt;&gt;&gt; ean = EAN(u'5901234123457', writer=ImageWriter())
  &gt;&gt;&gt; fullname = ean.save('ean13_barcode')
  </code></pre>
  
  <p>Last line generates following error:</p>
  
  <pre><code>Traceback (most recent call last):
    File "&lt;stdin&gt;", line 1, in &lt;module&gt;
    File "c:\python27\lib\site-packages\barcode\base.py", line 68, in save
      output = self.render(options)
    File "c:\python27\lib\site-packages\barcode\ean.py", line 106, in render
      return Barcode.render(self, options)
    File "c:\python27\lib\site-packages\barcode\base.py", line 103, in render
      raw = Barcode.raw = self.writer.render(code)
    File "c:\python27\lib\site-packages\barcode\writer.py", line 188, in render
      self._callbacks['paint_text'](xpos, ypos)
    File "c:\python27\lib\site-packages\barcode\writer.py", line 280, in _paint_te
  xt
      font = ImageFont.truetype(FONT, self.font_size * 2)
    File "c:\python27\lib\site-packages\PIL\ImageFont.py", line 218, in truetype
      return FreeTypeFont(filename, size, index, encoding)
    File "c:\python27\lib\site-packages\PIL\ImageFont.py", line 134, in __init__
      self.font = core.getfont(file, size, index, encoding)
    File "c:\python27\lib\site-packages\PIL\ImageFont.py", line 34, in __getattr__
  
      raise ImportError("The _imagingft C module is not installed")
  ImportError: The _imagingft C module is not installed
  </code></pre>
  
  <p>I retried by installing Pillow (but before that I removed PIL); I downloaded "Pillow-4.2.1-win32-py2_7.exe" 
  and I did also "pip install Pillow". </p>
  
  <p>Now when I try to run</p>
  
  <pre><code>import barcode
  </code></pre>
  
  <p>I got:</p>
  
  <pre><code>  File "barcode\codex.py", line 12, in &lt;module&gt;
  
      from barcode.base import Barcode
  
    File "barcode\base.py", line 9, in &lt;module&gt;
  
      from barcode.writer import SVGWriter
  
    File "barcode\writer.py", line 12, in &lt;module&gt;
  
      import Image, ImageDraw, ImageFont
  
    File "c:\python27\lib\site-packages\PIL\Image.py", line 27, in &lt;module&gt;
  
      from . import VERSION, PILLOW_VERSION, _plugins
  
  ValueError: Attempted relative import in non-package
  </code></pre>
  
  <p>What should I do ?</p>
  
  <p>thanks</p>