feat(appellate parser): A variety of small improvements
feat(appellate parser): A variety of small improvements

1. Fixes syntax errors.
2. Adds basic functionality in parallel with district parser's design.
3. Patches the HtmlElement class to add a re_xpath function, with
   support for regular expressions within XPath queries.
4. Makes file callable.
5. First appellate table is now parsing, except for the case name.

(With my apologies for so much in one commit -- my IDE isn't making this
easy.)

freelawproject/juriscraper,freelawproject/juriscraper