Optimized layouts and bugfix

Optimized song and artist list item layouts
Hopefully fixed a NPE when deleting a track

app/src/main/res/layout/fragment_artist_view.xml

@@ -3,14 +3,12 @@
     android:id="@+id/fragment_album_view"
     xmlns:android="http://schemas.android.com/apk/res/android"
     android:layout_width="match_parent"
-    android:layout_height="match_parent"
-    android:padding="2dp">
+    android:layout_height="match_parent">
 
     <android.support.v7.widget.RecyclerView
         android:id="@+id/recycler_view"
         android:layout_width="match_parent"
         android:layout_height="match_parent"
         android:clipToPadding="false"
-        android:padding="2dp"
         android:scrollbars="vertical"/>
 </LinearLayout>