Added link to webpack project in README.
Duplicated a webpack-relevant subset of ./bin/handlebars, but without the need to call a command line script.  Allows us to pass in the source from webpack instead of a path to the file. This makes handlebars-loader a chainable loader, with source and input and source as output.
Merged into one file and cleaned everything up a bit.  Upgraded to UglifyJS2 just for fun.