Add https proxy support

To access "api.browserstack.com" behind a proxy it is needed to add a
https proxy.

Ref #39
Ref #45

lib/api.js

@@ -6,6 +6,7 @@ function ApiBaseClient(settings) {
 	this.server = {
 		host: "api.browserstack.com"
 	};
+	this.proxy = settings.proxy || null;
 	BaseClient.call(this, settings);
 }
 

lib/client.js

@@ -1,6 +1,7 @@
 var https = require("https");
 var http = require("http");
 var extend = require("./extend");
+var HttpsProxyAgent = require('https-proxy-agent');
 var userAgent = getUA();
 
 function getUA() {
@@ -34,6 +35,8 @@ BaseClient.prototype.request = function(options, data, fn) {
 
 	fn = fn || function() {};
 
+	var agent = (this.proxy) ? new HttpsProxyAgent(this.proxy) : null;
+
 	var reqOptions = extend({
 		host: this.server.host,
 		port: this.server.port,
@@ -43,7 +46,8 @@ BaseClient.prototype.request = function(options, data, fn) {
 			"content-type": "application/json",
 			"user-agent": userAgent,
 			"content-length": typeof data === "string" ? data.length : 0
-		}
+		},
+		agent: agent
 	}, options);
 
 	var req = (this.useHttp ? http : https).request(reqOptions, function(res) {

lib/screenshot.js

@@ -6,6 +6,7 @@ function ScreenshotClient(settings) {
 	this.server = {
 		host: "www.browserstack.com"
 	};
+	this.proxy = settings.proxy || null;
 	BaseClient.call(this, settings);
 }
 

package.json

@@ -14,7 +14,9 @@
   },
   "bugs": "https://github.com/scottgonzalez/node-browserstack/issues",
   "licence": "MIT",
-  "dependencies": {},
+  "dependencies": {
+    "https-proxy-agent": "1.0.0"
+  },
   "devDependencies": {
     "jscs": "2.8.0",
     "jshint": "2.8.0",

readme.md

@@ -16,7 +16,8 @@ npm install browserstack
 var BrowserStack = require("browserstack");
 var browserStackCredentials = {
 	username: "foo",
-	password: "p455w0rd!!1"
+	password: "p455w0rd!!1",
+	https_proxy: "http://optional.proxy:1234"
 };
 
 // REST API
@@ -36,6 +37,7 @@ automateClient.getBrowsers(function(error, browsers) {
 });
 
 // Screenshots API
+
 var screenshotClient = BrowserStack.createScreenshotClient(browserStackCredentials);
 
 screenshotClient.getBrowsers(function(error, browsers) {
@@ -154,6 +156,7 @@ Creates a new client instance.
 	* `password`: The password for the BrowserStack account.
 	* `version` (optional; default: `4`): Which version of the BrowserStack API to use.
 	* `server` (optional; default: `{ host: "api.browserstack.com", port: 80 }`): An object containing `host` and `port` to connect to a different BrowserStack API compatible service.
+	* `proxy` (optional; default: `null`): "http://myproxy.com:1234"
 
 #### client.getBrowsers(callback)