Event driven programming

Signed-off-by: Alex Dove <alexdovethgreat@gmail.com>
First cut at event driven logic

1) Added event listeners to server (app.js) for signatures table and
petitions table
2) Added Mustache.js to client and use to create client side event
handlers for petitions table, petition details, and signatures table

*Also did some restructuring (extra lib folder within
public/javascript) isn't necessary, so I removed it)