Pandoc-eqnos

* Added numbering equations by section for html (Issue 15).

* For html, write equation numbers in a span and justify them
right. Before, the equation numbers were written into
the equation. This is a big change in approach.

* Python 2.7.3 bug addressed with pandoc-xnos 0.7.
* Clarified purpose of this filter in README.md.

* Updated for pandoc 1.18 (pandoc-fignos Issue 30)

* Fixed metadata corruption bug (pandoc-fignos Issue 23).
* Fixed python 2.7 install on Windows (pandoc-fignos Issue 27).
* Require pandoc-xnos >= 0.5.

* Require pandoc-xnos >= 0.4.1