add a bower.json to publish this as a Bower package
add build folder back into develop branch to allow 'bower install roslibjs#develop'
Merge #89 into develop

Also add back build folder, so users can do ```bower install roslibjs#develop``` - this should also put #85 and #86 to rest.

[ ] [Register](http://bower.io/#registering-packages) roslibjs with bower