Powerpoint export updates

* Refactors ruby->java interface to use JSON for data exchange
* Revisions to powerpoint formatting for better consistency across office suites (MS-Office, LibreOffice, OpenOffice, Keynote, & PDF export)
    * Replace carriage return bullets with individual metadata labels
    * Enhance & simplify text resizing for better compatibility 
    * Other minor formatting fixes to enhance compatibility across office suites