chore: set minimal node version to 8 (#847)

Author: Dmitry Nikulin

README.md

@@ -54,7 +54,7 @@ This module uses node.js, and can be installed through npm:
 npm install --save ipfs-api
 ```
 
-**Note:** ipfs-api requires Node.js v6 (LTS) or higher.
+We support both the Current and Active LTS versions of Node.js. Please see [nodejs.org](https://nodejs.org/) for what these currently are.
 
 ### Running the daemon with the right port
 

package.json

@@ -64,7 +64,7 @@
     "tar-stream": "^1.6.1"
   },
   "engines": {
-    "node": ">=6.0.0",
+    "node": ">=8.0.0",
     "npm": ">=3.0.0"
   },
   "repository": {