Feature/move to node 8.11.0 (#72)

* Update nodejs version in .travis

* Add some link in badges README

* Update packge-lock file

.travis.yml

@@ -1,6 +1,6 @@
 language: node_js
 node_js:
-    - "8.9.0"
+    - "8.11.0"
 install:
     - npm install
 before_script:

README.md

@@ -3,8 +3,8 @@
 [![npm version](https://img.shields.io/npm/v/react-d3-graph.svg?style=flat-square)](https://www.npmjs.com/package/react-d3-graph) [![probot enabled](https://img.shields.io/badge/probot:stale-enabled-yellow.svg?longCache=true&style=flat-square)](https://probot.github.io/) [![trello](https://img.shields.io/badge/trello-board-blue.svg?longCache=true&style=flat-square)](https://trello.com/b/KrnmFXha/react-d3-graph)
 [![code style: prettier](https://img.shields.io/badge/code_style-prettier-ff69b4.svg?style=flat-square)](https://github.com/prettier/prettier)
 
-![npm](https://img.shields.io/npm/dw/react-d3-graph.svg?style=flat-square)
-![npm](https://img.shields.io/npm/dt/react-d3-graph.svg?style=flat-square)
+[![npm](https://img.shields.io/npm/dw/react-d3-graph.svg?style=flat-square)](https://www.npmjs.com/package/react-d3-graph)
+[![npm](https://img.shields.io/npm/dt/react-d3-graph.svg?style=flat-square)](https://www.npmjs.com/package/react-d3-graph)
 
 :book: [1.2.1](https://danielcaldas.github.io/react-d3-graph/docs/index.html)