code: function list (existsPath) {
      return new Q.Promise(function (resolve, reject) {
        fs.access(existsPath, function (err) {
          resolve(!err)
        })
      })
    }
docs: Custom implementation of [q-io/fs#exists](http://documentup.com/kriskowal/q-io#lexistsPath)
  to avoid dependency on q-io
  @param {string} existsPath the path to check
  @returns {Promise<boolean>} a promise for the existance (true/false) of the file/dir at the path