Fix null duration

AndroidManifest.xml

@@ -2,8 +2,8 @@
 <manifest xmlns:a="http://schemas.android.com/apk/res/android"
     package="com.thejoshwa.ultrasonic.androidapp"
     a:installLocation="auto"
-    a:versionCode="28"
-    a:versionName="1.2.0.1" >
+    a:versionCode="29"
+    a:versionName="1.2.0.2" >
 
     <uses-permission a:name="android.permission.INTERNET" />
     <uses-permission a:name="android.permission.READ_PHONE_STATE" />

src/com/thejoshwa/ultrasonic/androidapp/domain/MusicDirectory.java

@@ -254,7 +254,7 @@ public class MusicDirectory {
         }
 
         public Integer getDuration() {
-            return duration;
+            return duration == null ? 0 : duration;
         }
 
         public void setDuration(Integer duration) {