title: pip install boilerpipe failed with tarfile.ReadError: empty file
body: <p>I'm try to install boilerpipe through pip but it failed.</p>
  
  <p>here is the log.</p>
  
  <p>Complete output from command python setup.py egg_info:</p>
  
  <pre><code>Traceback (most recent call last):
    File "&lt;string&gt;", line 20, in &lt;module&gt;
    File "/tmp/pip-build-J2gFYC/boilerpipe/setup.py", line 27, in &lt;module&gt;
      download_jars(datapath=DATAPATH)
    File "/tmp/pip-build-J2gFYC/boilerpipe/setup.py", line 21, in download_jars
      tar = tarfile.open(tgz_name, mode='r:gz')
    File "/usr/lib/python2.7/tarfile.py", line 1678, in open
      return func(name, filemode, fileobj, **kwargs)
    File "/usr/lib/python2.7/tarfile.py", line 1727, in gzopen
      **kwargs)
    File "/usr/lib/python2.7/tarfile.py", line 1705, in taropen
      return cls(name, mode, fileobj, **kwargs)
    File "/usr/lib/python2.7/tarfile.py", line 1574, in __init__
      self.firstmember = self.next()
    File "/usr/lib/python2.7/tarfile.py", line 2334, in next
      raise ReadError("empty file")
  tarfile.ReadError: empty file
  
  ----------------------------------------
  </code></pre>
  
  <p>Command "python setup.py egg_info" failed with error code 1 in /tmp/pip-build-J2gFYC/boilerpipe</p>