Insert variable to groovy strings for versions

Allows Android Studio to hint for available library upgrades

api/build.gradle

@@ -46,6 +46,6 @@ task generateSources (type: Jar) {
 
 dependencies {
     compile fileTree(dir: 'libs', include: ['*.jar'])
-    compile 'com.android.support:appcompat-v7:'+rootProject.ext.appCompatVersion
+    compile "com.android.support:appcompat-v7:$rootProject.ext.appCompatVersion"
     testCompile 'junit:junit:4.12'
 }

libvlc/build.gradle

@@ -104,5 +104,5 @@ clean {
 }
 
 dependencies {
-    compile 'com.android.support:support-annotations:'+rootProject.ext.appCompatVersion
+    compile "com.android.support:support-annotations:$rootProject.ext.appCompatVersion"
 }

medialibrary/build.gradle

@@ -63,7 +63,7 @@ clean {
 
 dependencies {
     compile project(':libvlc')
-    compile 'com.android.support:support-v4:'+rootProject.ext.appCompatVersion
-    compile 'com.android.support:support-compat:'+rootProject.ext.appCompatVersion
-    compile 'com.android.support:support-fragment:'+rootProject.ext.appCompatVersion
+    compile "com.android.support:support-v4:$rootProject.ext.appCompatVersion"
+    compile "com.android.support:support-compat:$rootProject.ext.appCompatVersion"
+    compile "com.android.support:support-fragment:$rootProject.ext.appCompatVersion"
 }

vlc-android/build.gradle

@@ -180,14 +180,13 @@ dependencies {
     compile project(':medialibrary')
     compile project(':api')
     compile project(':axmlrpc')
-    compile 'com.android.support:appcompat-v7:'+rootProject.ext.appCompatVersion
-    compile 'com.android.support:recyclerview-v7:'+rootProject.ext.appCompatVersion
-    compile 'com.android.support:design:'+rootProject.ext.appCompatVersion
-    compile 'com.android.support:support-annotations:'+rootProject.ext.appCompatVersion
-    compile 'com.android.support:preference-v7:'+rootProject.ext.appCompatVersion
-    compile 'com.android.support:leanback-v17:'+rootProject.ext.appCompatVersion
-    compile 'com.android.support:preference-leanback-v17:'+rootProject.ext.appCompatVersion
-    compile 'com.android.support.constraint:constraint-layout:'+rootProject.ext.constraintLayoutVersion
+    compile "com.android.support:recyclerview-v7:$rootProject.ext.appCompatVersion"
+    compile "com.android.support:design:$rootProject.ext.appCompatVersion"
+    compile "com.android.support:support-annotations:$rootProject.ext.appCompatVersion"
+    compile "com.android.support:preference-v7:$rootProject.ext.appCompatVersion"
+    compile "com.android.support:leanback-v17:$rootProject.ext.appCompatVersion"
+    compile "com.android.support:preference-leanback-v17:$rootProject.ext.appCompatVersion"
+    compile "com.android.support.constraint:constraint-layout:$rootProject.ext.constraintLayoutVersion"
     testCompile 'junit:junit:4.12'
 }