Upgrading versions as discussed in github.com/gruntjs/grunt-contrib-jshint/issues/92 solved the problem.
Also as @Dexa pointed out, for him - removal of scripts
part of the package.json worked and adding following to the Gruntfile.js :
grunt.registerTask('default', ['jshint']);
For clarification, ^ above registers default grunt task to run jshint when grunt
is wrote to command line.