Updated py-lxml to 3.7.2.

==============
lxml changelog
==============

3.7.2 (2017-01-08)
==================

Bugs fixed
----------

* Work around installation problems in recent Python 2.7 versions
  due to FTP download failures.

* GH#219: ``xmlfile.element()`` was not properly quoting attribute values.
  Patch by Burak Arslan.

* GH#218: ``xmlfile.element()`` was not properly escaping text content of
  script/style tags.  Patch by Burak Arslan.

(wiz)