refactor: Rewrite all source in javascript.

Convert everything in /src from coffeescript to Javascript.  Replace coffee build process with
Babel.  Remove most of our dependencies.

BREAKING CHANGE: Officially dropping support for node v4.x.x.

.babelrc

@@ -0,0 +1,8 @@
+{
+    "presets": [
+        ["env", {"targets": {"node": "6"}}]
+    ],
+    "env": {
+        "test": { "plugins": ["istanbul"] }
+    }
+}

.gitignore

@@ -2,3 +2,4 @@
 /lib
 /npm-debug.log
 /coverage
+/.nyc_output

.nycrc

@@ -0,0 +1,7 @@
+{
+    "require": ["babel-register"],
+    "include": ["src/**/*.js"],
+    "reporter": ["html", "text-summary", "lcov"],
+    "all": true,
+    "instrument": false
+}

examples/receiver.js

@@ -1,4 +1,3 @@
-Promise = global.Promise || require('es6-promise').Promise;
 var amqp = require('..');
 
 var QUEUE_NAME = 'amqp-connection-manager-sample1'

examples/sender.js

@@ -1,4 +1,3 @@
-Promise = global.Promise || require('es6-promise').Promise;
 var amqp = require('..');
 var wait = require('../lib/helpers').wait;