Implement support for standard Grunt-0.4 file mappings and options.
Implement support for standard Grunt-0.4 file mappings and options.

See https://github.com/gruntjs/grunt/wiki/Configuring-tasks#files and https://github.com/gruntjs/grunt/wiki/Configuring-tasks#options for details.
Retains backwards compatibility with existing grammar/outputFile/exportVar configuration format.
felixhao28/grunt-peg,dvberkel/grunt-peg