Handle "hasOwnProperty" global variable

If the user adds "hasOwnProperty" as a global variable, an error is thrown because JSHINT.blacklist.hasOwnProperty is no longer a function, but a string. By calling the original Object prototype, the correct function is called and jshint won't crash.

This fixes an issue in another repository: https://github.com/spenceralger/gulp-jshint/issues/39, and various libraries like AngularJS who define hasOwnProperty as a global won't crash jshint.

Ran npm test successfully: "OK: 974 assertions (4073ms)"