code: function isClean() {
      var args = [
        'diff-index',
        '--quiet',
        'HEAD',
        '.'
      ];
  
      return git(args)
          .then(function() {
            return true;
          })
          .catch(function(err) {
            if (err.code === 1) {
              return false;
            }
            return Promise.reject(err);
          });
    }
docs: Gets the current workspace is clean or has something in the working tree
  Executes `git diff-index --quiet HEAD .`
  
  @example
  var git = require('gitftw');
  
  git.isClean()
  .then(function(clean) {
  if (clean) {
  console.log('The git workspace is clean');
  } else {
  console.log('The git workspace is dirty');
  }
  });
  
  @memberof git
  @type {command}
  
  @param {callback} [cb] The execution callback result
  @returns {Promise} Promise Resolves with true if the workspace is clean.
  false otherwise