Updated CAKEFILE - change 'package' to 'pkg'

As per https://github.com/jashkenas/coffee-script/blob/master/src/lexer.coffee#L596, 'package' is not a valid coffee-script identifier due to its status as , being a future reserved javascript keyword since ECMA-5. Thus all build tasks were failing (at lest subsequent to https://github.com/jashkenas/coffee-script/commit/0b7cfba94acef51440941880fe22a587cc1e6a8f) with cake with throwing a syntax error on line 5.