update dependencies and add david-dm badge (#106)

* update dependencies and add david-dm badge
* update devDependencies
* start testing on Node.js v7.x

.travis.yml

@@ -3,9 +3,9 @@ language: node_js
 node_js:
   - "0.10"
   - "0.12"
-  - "iojs"
   - "4"
   - "6"
+  - "7"
 script:
   - npm test
   - npm run lint

README.md

@@ -2,6 +2,7 @@
 
 [![Build Status][travisimg]][travis]
 [![Code Coverage][coverallsimg]][coveralls]
+[![Dependencies][david-dm-img]][david-dm]
 
 This is Google's officially supported [node.js][node] client library for using
 OAuth 2.0 authorization and authentication with Google APIs.
@@ -130,3 +131,5 @@ available in [COPYING][copying].
 [coveralls]: https://coveralls.io/r/google/google-auth-library-nodejs?branch=master
 [coverallsimg]: https://img.shields.io/coveralls/google/google-auth-library-nodejs.svg
 [Application Default Credentials]: https://developers.google.com/identity/protocols/application-default-credentials#callingnode
+[david-dm-img]: https://david-dm.org/google/google-auth-library-nodejs/status.svg
+[david-dm]: https://david-dm.org/google/google-auth-library-nodejs

package.json

@@ -33,24 +33,23 @@
     "client library"
   ],
   "dependencies": {
-    "async": "~1.4.2",
+    "async": "^2.0.0",
     "gtoken": "^1.1.0",
-    "lodash.noop": "~3.0.0",
-    "jws": "~3.0.0",
-    "request": "~2.74.0",
-    "string-template": "~0.2.0"
+    "lodash.noop": "^3.0.0",
+    "jws": "^3.0.0",
+    "request": "^2.74.0",
+    "string-template": "^1.0.0"
   },
   "devDependencies": {
     "coveralls": "^2.11.1",
-    "istanbul": "~0.3.2",
-    "keypair": "~1.0.0",
+    "istanbul": "^0.3.2",
+    "keypair": "^1.0.0",
     "jshint": "^2.5.5",
-    "jsdoc": "~3.3.0-alpha9",
-    "mkdirp": "~0.5.0",
-    "mocha": "^1.8.1",
-    "nock": "~1.9.0",
+    "jsdoc": "^3.4.3",
+    "mkdirp": "^0.5.0",
+    "mocha": "^3.1.2",
+    "nock": "^9.0.2",
     "rimraf": "^2.2.8",
-    "url": "~0.10.1",
     "minimist": "^1.1.0"
   },
   "scripts": {