Use batman-rails-0.16.1 instead of vendored batman

Some changes were required to work with version 0.16.1. Mostly related to
widget initialization (construct, loadView, etc)
Revert version change
Include batman engine in our engine file
Also use batman's es5-shim
Change the way widgets are initialized

Attaching the initialization entry point to the first change in
Dashing.Widget.node. This occurs right after widget construction in recent
batman releases (0.15.0+) and seems more reliable and logical than the
loadNode method.
Merge pull request #56 from ravishi/use-batman-rails

Use batman-rails instead of vendored batman