add gitpod and fix gitmodules

.gitmodules

@@ -1,3 +1,3 @@
 [submodule "ProtoDef"]
 	path = ProtoDef
-	url = git@github.com:ProtoDef-io/ProtoDef.git
+	url = https://github.com/ProtoDef-io/ProtoDef.git

.gitpod.yml

@@ -0,0 +1,2 @@
+tasks:
+- command: npm install

README.md

@@ -5,6 +5,7 @@
 [![Irc](https://img.shields.io/badge/chat-on%20irc-brightgreen.svg)](https://irc.gitter.im/)
 [![Build Status](https://img.shields.io/circleci/project/github/ProtoDef-io/node-protodef/master.svg)](https://circleci.com/gh/ProtoDef-io/node-protodef)
 [![Tonic](https://img.shields.io/badge/tonic-try%20it-blue.svg)](https://tonicdev.com/npm/protodef)
+[![Try it on gitpod](https://img.shields.io/badge/try-on%20gitpod-brightgreen.svg)](https://gitpod.io/#https://github.com/ProtoDef-io/node-protodef)
 
 This is a node.js module to simplify defining, reading and writing binary blobs,
 whether they be internet protocols or files.
@@ -40,4 +41,4 @@ See the language independent [ProtoDef](https://github.com/ProtoDef-io/ProtoDef)
 * [node-raknet](https://github.com/mhsjlw/node-raknet) describe the raknet protocol in a protocol.json and uses ProtoDef to read it
 * [minecraft-classic-protocol](https://github.com/mhsjlw/minecraft-classic-protocol) defines the classic minecraft protocol with ProtoDef
 * [pocket-minecraft-protocol](https://github.com/mhsjlw/pocket-minecraft-protocol) defines the minecraft pocket edition protocol
- 
+