Mammoth

* Add the function `mammoth.extract_raw_text`.

* Add support for tables

* Rename --styles CLI argument to --style-map.

* Rename styles argument in convert_to_html to style_map.

* Allow paragraphs and runs to be matched by style name. For instance, to match
a paragraph with the style name `Heading 1`:

p[style-name='Heading 1']

* Fix: exception when bad arguments are passed into unzip.openZip.

* Fix browserify support.

* Rename mammoth.style() to mammoth.styleMapping().

* Add support for document transforms.

* Append standard style map to custom style map unless explicitly excluded.