Log Message:
Update py-weasyprint to 0.26.

Version 0.26
------------

Released on 2016-01-29.

New features:

* Support the `empty-cells` attribute.
* Respect table, column and cell widths.

Bug fixes:

* `#172: <https://github.com/Kozea/WeasyPrint/issues/172>`_:
  Unable to set table column width on tables td's.
* `#151: <https://github.com/Kozea/WeasyPrint/issues/151>`_:
  Table background colour bleeds beyond table cell boundaries.
* `#260: <https://github.com/Kozea/WeasyPrint/issues/260>`_:
  TypeError: unsupported operand type(s) for +: 'float' and 'str'.
* `#288: <https://github.com/Kozea/WeasyPrint/issues/288>`_:
  Unwanted line-breaks in bold text.
* `#286: <https://github.com/Kozea/WeasyPrint/issues/286>`_:
  AttributeError: 'Namespace' object has no attribute 'attachments'.