Rework Docker support

- Use multi-stage build for the application image
- Utilize connection pool init timeout for waiting on database container startup,
"docker-compose-wait" dependency is no longer required
- Override database host through environment variable - used in docker-compose
- Rename database scripts for explicit ordering (db container loads them alphabetically)

src/main/java/config/ServerConfig.java

@@ -5,7 +5,8 @@ public class ServerConfig {
     public boolean USE_THREAD_TRACKER;
 
     //Database Configuration
-    public String DB_URL;
+    public String DB_URL_FORMAT;
+    public String DB_HOST;
     public String DB_USER;
     public String DB_PASS;
     public int INIT_CONNECTION_POOL_TIMEOUT;