Bump up DATABASE_VERSION to create new tables for emoji in the existing database

Author: kunall17

app/src/main/java/com/zulip/android/database/DatabaseHelper.java

@@ -30,7 +30,7 @@ public class DatabaseHelper extends OrmLiteSqliteOpenHelper {
     private static final String DATABASE_NAME = "zulip-%s.db";
     // any time you make changes to your database objects, you may have to
     // increase the database version
-    private static final int DATABASE_VERSION = 3;
+    private static final int DATABASE_VERSION = 4;
 
     public DatabaseHelper(ZulipApp app, String email) {
         super(app, String.format(DATABASE_NAME, MD5Util.md5Hex(email)), null,