[REEF-778] IMRU Map and Update task and driver have verbose setting o…

…n by default

This addressed the issue by
* Setting DriverConfiguration.CustomTraceLevel to Info

JIRA:[REEF-778](https://issues.apache.org/jira/browse/REEF-778)

This Closes apache#517

lang/cs/Org.Apache.REEF.IMRU/OnREEF/Client/REEFIMRUClient.cs

@@ -23,6 +23,7 @@
 using Org.Apache.REEF.Client.API;
 using Org.Apache.REEF.Driver;
 using Org.Apache.REEF.IMRU.API;
+using Org.Apache.REEF.Driver.Bridge;
 using Org.Apache.REEF.IMRU.OnREEF.Driver;
 using Org.Apache.REEF.IMRU.OnREEF.Parameters;
 using Org.Apache.REEF.Network.Group.Config;
@@ -95,6 +96,7 @@ internal sealed class REEFIMRUClient<TMapInput, TMapOutput, TResult> : IIMRUClie
                         GenericType<IMRUDriver<TMapInput, TMapOutput, TResult>>.Class)
                     .Set(DriverConfiguration.OnEvaluatorFailed,
                         GenericType<IMRUDriver<TMapInput, TMapOutput, TResult>>.Class)
+                    .Set(DriverConfiguration.CustomTraceLevel, TraceLevel.Info.ToString())
                     .Build(),
                 TangFactory.GetTang().NewConfigurationBuilder()
                     .BindStringNamedParam<GroupCommConfigurationOptions.DriverId>(driverId)