Post about NDoCH and Open Trail Data projects

This a draft of a post promoting the National Day of Civic Hacking event letting people know about PLATS and the guests we're expecting to fly up for our event. @mbcharbonneau, when you get a chance can you review this and add whatever you like? You can post edits as comments or get crazy and fork off my branch.

@elauervose @milkandtang @pdxmele @donpdonp feel free to add thoughts. This was hastily drafted between conference events. I left it wide open at the end for @mbcharbonneau to go into specifics if he's already got ideas.