fix linting errors

lib/6to5/detection/index.js

@@ -1,6 +1,6 @@
 module.exports = detect;
 
-var useragent = require("useragent");
+//var useragent = require("useragent");
 var traverse  = require("../traverse");
 
 var SYNTAX_KEYS = require("./syntax-keys");

lib/6to5/transformation/transformer.js

@@ -7,7 +7,6 @@ var isFunction      = require("lodash/lang/isFunction");
 var traverse        = require("../traverse");
 var isObject        = require("lodash/lang/isObject");
 var each            = require("lodash/collection/each");
-var t               = require("../types");
 
 /**
  * This is the class responsible for normalising a transformers handlers

lib/6to5/transformation/transformers/es6/block-scoping.js

@@ -2,7 +2,6 @@
 
 var traverse = require("../../../traverse");
 var object   = require("../../../helpers/object");
-var clone    = require("lodash/lang/clone");
 var util     = require("../../../util");
 var t        = require("../../../types");
 var values   = require("lodash/object/values");