Reverting the cache version change, so that users on release version do not get the cache reset

Change-Id: I61b06ca001e6ae47693e8d6f467565314d66f1b4

src/com/android/launcher3/IconCache.java

@@ -782,7 +782,7 @@ public class IconCache {
     }
 
     private static final class IconDB extends SQLiteOpenHelper {
-        private final static int DB_VERSION = 8;
+        private final static int DB_VERSION = 7;
 
         private final static String TABLE_NAME = "icons";
         private final static String COLUMN_ROWID = "rowid";