Use proxy-lib package when working behind proxy

The `proxy-lib` package provides required methods for setting and getting proxy. Its implementation is more secure when stroing credentials, so switch to it instead of current implementation.
Remove the credentials-manager from CLI as it is no longer needed.
Remove the CredentialsManager.exe as well and its source code.

Fix the error `Cannot read property ExceptionMessage of null` when wokring behind proxy - add correct null checks.

Fix tracking to google analytics behind proxy - pass the proxy URL to Universal Analytics module.

Author: rosen-vladimirov

lib/common

@@ -432,14 +432,6 @@ interface IInfoService {
 	printComponentsInfo(): Promise<void>;
 }
 
-/**
- * Describes standard username/password type credentials.
- */
-interface ICredentials {
-	username: string;
-	password: string;
-}
-
 /**
  * Describes properties needed for uploading a package to iTunes Connect
  */

lib/declarations.d.ts

@@ -10,7 +10,8 @@ export class GoogleAnalyticsProvider implements IGoogleAnalyticsProvider {
 	constructor(private clientId: string,
 		private $staticConfig: IStaticConfig,
 		private $analyticsSettingsService: IAnalyticsSettingsService,
-		private $logger: ILogger) {
+		private $logger: ILogger,
+		private $proxyService: IProxyService) {
 	}
 
 	public async trackHit(trackInfo: IGoogleAnalyticsData): Promise<void> {
@@ -27,11 +28,16 @@ export class GoogleAnalyticsProvider implements IGoogleAnalyticsProvider {
 	}
 
 	private async track(gaTrackingId: string, trackInfo: IGoogleAnalyticsData, sessionId: string): Promise<void> {
+		const proxySettings = await this.$proxyService.getCache();
+		const proxy = proxySettings && proxySettings.proxy;
 		const visitor = ua({
 			tid: gaTrackingId,
 			cid: this.clientId,
 			headers: {
 				["User-Agent"]: this.$analyticsSettingsService.getUserAgentString(`tnsCli/${this.$staticConfig.version}`)
+			},
+			requestOptions: {
+				proxy
 			}
 		});
 

lib/services/analytics/google-analytics-provider.ts

@@ -64,6 +64,7 @@
     "plistlib": "0.2.1",
     "progress-stream": "1.1.1",
     "properties-parser": "0.2.3",
+    "proxy-lib": "0.1.0",
     "qr-image": "3.2.0",
     "request": "2.81.0",
     "semver": "5.3.0",