Fix Bullet Behavior on export

* Use JSON for data transfer between ruby and java
* Explicitly generate metadata lines rather than using carriage returns for bulleting
* Support arbitrary numbers of creator, date, and description elements on each slide
* Resize text to fix on slide as necessary
* Modularize metadata formatting to simplify future changes
* Misc changes attempting to make MS-Office, LibreOffice, OpenOffice, and PDF output more consistent
FYI:  Rails has a method called blank? that you could use to cover both those cases, so you could shorten this line to:
```if image_path.blank? ```
http://api.rubyonrails.org/classes/Object.html#method-i-blank-3F