Pipeline integration

Work done to enable PETRARCH to drop into the processing pipeline. Mainly this is:

* Make PETRARCH accept the input format of the database connection
* Integrate StanfordNLP so we can parse plain text
* Define an output format that PETRARCH can return to the pipeline
  * This is optional. The PETRARCH can also write directly from the pipeline to a text file.

There's some things left undone on the XML and StanfordNLP side of things, but that will happen in another PR.