Added more classes to api.auth package, removed dep on slf4j-api from services-api

Author: artem-v

services-api/src/main/java/io/scalecube/services/methods/ServiceMethodInvoker.java

@@ -160,8 +160,7 @@ private Mono<Object> authenticate(ServiceMessage message, Context context) {
       if (context.hasKey(AUTH_CONTEXT_KEY)) {
         return Mono.just(context.get(AUTH_CONTEXT_KEY));
       } else {
-        throw new UnauthorizedException(
-            "Authentication failed (auth context not found and authenticator not set)");
+        throw new UnauthorizedException("Authentication failed");
       }
     }
 

services/src/test/java/io/scalecube/services/ServiceCallLocalTest.java

@@ -19,6 +19,7 @@
 import io.scalecube.services.api.ServiceMessage;
 import io.scalecube.services.discovery.ScalecubeServiceDiscovery;
 import io.scalecube.services.exceptions.ServiceException;
+import io.scalecube.services.exceptions.ServiceUnavailableException;
 import io.scalecube.services.registry.api.ServiceRegistry;
 import io.scalecube.services.routing.RoundRobinServiceRouter;
 import io.scalecube.services.sut.EmptyGreetingResponse;
@@ -183,8 +184,11 @@ public void test_async_greeting_return_string_service_not_found_error_case() {
       Mono.from(service.requestOne(NOT_FOUND_REQ)).block(timeout);
       fail("Expected no-service-found exception");
     } catch (Exception ex) {
-      assertEquals(
-          ex.getMessage(), "No reachable member with such service: " + NOT_FOUND_REQ.qualifier());
+      assertEquals(ServiceUnavailableException.class, ex.getClass());
+      assertNotNull(ex.getMessage());
+      assertTrue(
+          ex.getMessage()
+              .startsWith("No reachable member with such service: " + NOT_FOUND_REQ.qualifier()));
     }
   }