Remove potential Unicode BOM

This pull request strips potential unicode BOM from the files before passing it to jshint as jshint cli does ([link to code](https://github.com/jshint/jshint/blob/master/src/cli.js#L483)) and as suggested by nodejs developers ([link](https://github.com/joyent/node/issues/1918)). This is needed because some text editors insist on setting the BOM (e.g. Visual Studio).