Merge pull request #821 from NativeScript/fatme/fix-tns-doctor

Fix tns doctor command when javac is not added to PATH

Author: Fatme

lib/common

@@ -1,7 +1,7 @@
 ///<reference path="../.d.ts"/>
 "use strict";
 import {EOL} from "os";
-import * as semver from "semver";
+import * as helpers from "../common/helpers";
 
 class DoctorService implements IDoctorService {
 	private static MIN_SUPPORTED_GRADLE_VERSION = "2.3";
@@ -70,7 +70,8 @@ class DoctorService implements IDoctorService {
 			this.$logger.out("You will not be able to build your projects for Android or run them in the emulator or on a connected device." + EOL
 				+ "To be able to build for Android and run apps in the emulator on on a connected device, verify that you have installed Gradle.");
 		}
-		if(sysInfo.gradleVer && semver.lt(sysInfo.gradleVer, DoctorService.MIN_SUPPORTED_GRADLE_VERSION)) {
+		
+		if(sysInfo.gradleVer && helpers.versionCompare(sysInfo.gradleVer, DoctorService.MIN_SUPPORTED_GRADLE_VERSION) === -1) {
 			this.$logger.warn(`WARNING: Gradle version is lower than ${DoctorService.MIN_SUPPORTED_GRADLE_VERSION}.`);
 			this.$logger.out("You will not be able to build your projects for Android or run them in the emulator or on a connected device." + EOL
 				+ `To be able to build for Android and run apps in the emulator on on a connected device, verify thqt you have at least ${DoctorService.MIN_SUPPORTED_GRADLE_VERSION} version installed.`);