Merge pull request zo0r#1170 from owinter86/patch-1

Fix undefined fallback variables in build gradle

Author: zo0r

android/build.gradle

@@ -43,9 +43,9 @@ android {
 }
 
 dependencies {
-    def supportLibVersion = project.hasProperty('supportLibVersion') ? project.supportLibVersion : DEFAULT_SUPPORT_LIB_VERSION
-    def googlePlayServicesVersion = project.hasProperty('googlePlayServicesVersion') ? project.googlePlayServicesVersion : DEFAULT_GOOGLE_PLAY_SERVICES_VERSION
-    def firebaseVersion = project.hasProperty('firebaseVersion') ? project.firebaseVersion : DEFAULT_FIREBASE_MESSAGING_VERSION
+    def supportLibVersion = safeExtGet('supportLibVersion', '27.1.1')
+    def googlePlayServicesVersion = safeExtGet('googlePlayServicesVersion', '+')
+    def firebaseVersion = safeExtGet('firebaseVersion', '+')
 
     implementation fileTree(dir: 'libs', include: ['*.jar'])
     testImplementation 'junit:junit:4.12'