adds Javascript MAVLink generator
cleanup before issuing pull request
Improves example code in readme
remove copy of jspack lib, add x25crc to core

This removes the static copy of the jspack lib, adding it as an npm dependency.  Also, this removes the stub 'mavutil' object, which only contained the x25crc function, which has been added to the mavlink object.
Generator now creates npm modules for each implementation
improves README to show how to send messages
Merge pull request #107 from acuasi/javascript

Javascript MAVLink generator for Node.js