Add es6-promise dependency

Since it needed only for node version.

README.md

@@ -4,12 +4,6 @@ JavaScript Bitmessage library for both browserify and node.
 
 ## Usage
 
-You need ES6 Promise available in order to use this module. Use some sort of ES6 runtime or just apply polyfill:
-
-```js
-require("es6-promise").polyfill();
-```
-
 ```js
 var bitmessage = require("bitmessage");
 ```

lib/crypto.js

@@ -7,6 +7,7 @@
 
 "use strict";
 
+var Promise = require("es6-promise").Promise;  // jshint ignore:line
 var crypto = require("crypto");
 
 exports.sha512 = function(buf) {

package.json

@@ -27,8 +27,10 @@
   "homepage": "https://github.com/nekogrid/bitmessage",
   "devDependencies": {
     "chai": "*",
-    "es6-promise": "^2.0.1",
     "jshint": "*",
     "mocha": "*"
+  },
+  "dependencies": {
+    "es6-promise": "^2.0.1"
   }
 }

test.js

@@ -1,11 +1,10 @@
 var expect = require("chai").expect;
 
-require("es6-promise").polyfill();
+var bmcrypto = require("./lib/crypto");
-var crypto = require("./lib/crypto");
 
-describe("crypto", function() {
+describe("Bitmessage crypto", function() {
   it("should calculate sha512 hash for both node and browserify", function(done) {
-    crypto.sha512(new Buffer("test")).then(function(res) {
+    bmcrypto.sha512(new Buffer("test")).then(function(res) {
       expect(res.toString("hex")).to.equal("ee26b0dd4af7e749aa1a8ee3c10ae9923f618980772e473f8819a5d4940e0db27ac185f8a0e1d5f84f88bc887fd67b143732c304cc5fa9ad8e6f57f50028a8ff");
       done();
     });