EST: map exceptions to proper HTTP responses

Use PKIExceptionMapper to map the various web application exceptions
to the corresponding HTTP response types.

Part of: dogtagpki#3297

base/est/src/main/java/org/dogtagpki/est/ESTApplication.java

@@ -11,6 +11,8 @@
 import javax.ws.rs.ApplicationPath;
 import javax.ws.rs.core.Application;
 
+import org.dogtagpki.server.rest.PKIExceptionMapper;
+
 @ApplicationPath("")
 public class ESTApplication extends Application {
 
@@ -22,6 +24,9 @@ public class ESTApplication extends Application {
     public ESTApplication() {
         logger.info("Initializing ESTApplication");
         classes.add(ESTFrontend.class);
+
+        // exception mapper
+        classes.add(PKIExceptionMapper.class);
     }
 
     @Override