Integrate the GROBID PDF extractor in Tika

GROBID (http://grobid.readthedocs.org/en/latest/) is a machine learning library for extracting, parsing and re-structuring raw documents such as PDF into structured TEI-encoded documents with a particular focus on technical and scientific publications.
It has a java api which can be used to augment PDF parsing for journals and help extract extra metadata about the paper like authors, publication, citations, etc.

It would be nice to have this integrated into Tika, I have tried it on my local, will issue a pull request soon.