fix: detect java correctly

In case you have incorrect JAVA_HOME, but you have `javac` in PATH, CLI's doctor checks will allow you to build, but Gradle will fail. Fix the logic to be the same as the one used in Gradle.

Author: rosen-vladimirov

npm-shrinkwrap.json

@@ -57,7 +57,7 @@
     "mkdirp": "0.5.1",
     "mute-stream": "0.0.5",
     "nativescript-dev-xcode": "0.1.0",
-    "nativescript-doctor": "1.9.1",
+    "nativescript-doctor": "1.9.2",
     "nativescript-preview-sdk": "0.3.3",
     "open": "0.0.5",
     "ora": "2.0.0",

package.json

@@ -3720,10 +3720,10 @@ [email protected]:
     simple-plist "^1.0.0"
     uuid "^3.3.2"
 
-[email protected].1:
-  version "1.9.1"
-  resolved "https://registry.yarnpkg.com/nativescript-doctor/-/nativescript-doctor-1.9.1.tgz#42ac6b15f7b1531d2fe07d32a30e50b89cf46bbb"
-  integrity sha512-qdluBILhzAQhnIg8Y83syyjy63rTt5pvx0SFpbtwj7kE+LsXJJRhHNa+1KEtznxh7jcTfdLEZjxxWDTIAIK5oA==
+[email protected].2:
+  version "1.9.2"
+  resolved "https://registry.yarnpkg.com/nativescript-doctor/-/nativescript-doctor-1.9.2.tgz#a3b5b06c82bc20bf7bfde04552f3d52739229e85"
+  integrity sha512-HEBQS7eqycO3TzY3He94dM0AgPCQy3YMT6ZdHSVGDfxA5DhnhMgB0OWOvHPwR3TyL0BJhtLJnjrW4/hJjUw2SQ==
   dependencies:
     osenv "0.1.3"
     semver "5.5.1"