Updated properties such that agenda be a .pdf

Now the default agenda name is a .pdf instead of a .docx.
Removed POI dependencies, added PDFBox

updated dependencies.
Updated README to reflect change to pdf.
Now sends PDF file instead of DOCX Agenda

made a change to the file type that is generated for the agenda.  PDF is
a more cross-platform file format that is more easily viewed by all
users, and reduced the number of dependencies required for this project
by a great number.