DevGuide chapter 2 formatted and preface removed

Hi Russ. I made a bunch of formatting changes to 02-plugins-sdk.markdown that should be a good representative of things to apply throughout the guide. You'll be getting emails from me with inline comments that I'll put in my commit that highlight the types of changes.

I refactored the Ant configuration section as I did the same thing with our training slides recently.

Lastly, I removed the 00-preface.markdown as we don't need it for our online docs. I'll follow Rich's example in the Latex version of Using Liferay Portal for the Dev Guide's Latex file.