Add support for delete favorite and user withheld

[dennislloydjr]

Related to issue: #66

When the compliance stream receives a delete favorite event, the following exception is thrown:

WARN  [] c.z.g.api.impl.DefaultGnipStream {} - Unexpected exception while consuming activity stream {your-stream-name}: null
[10.100.6.81] out: java.lang.NullPointerException: null
[10.100.6.81] out: 	at com.zaubersoftware.gnip4j.api.model.compliance.DeleteStatusActivity$Status.access$000(DeleteStatusActivity.java:38) ~[gnip4j-core-2.1.0.jar:na]
[10.100.6.81] out: 	at com.zaubersoftware.gnip4j.api.model.compliance.DeleteStatusActivity.toActivity(DeleteStatusActivity.java:49) ~[gnip4j-core-2.1.0.jar:na]
[10.100.6.81] out: 	at com.zaubersoftware.gnip4j.api.impl.formats.ComplianceActivityUnmarshaller.unmarshall(ComplianceActivityUnmarshaller.java:42) ~[gnip4j-core-2.1.0.jar:na]
[10.100.6.81] out: 	at com.zaubersoftware.gnip4j.api.impl.formats.ComplianceActivityUnmarshaller.unmarshall(ComplianceActivityUnmarshaller.java:35) ~[gnip4j-core-2.1.0.jar:na]
[10.100.6.81] out: 	at com.zaubersoftware.gnip4j.api.impl.formats.ByLineFeedProcessor.process(ByLineFeedProcessor.java:53) ~[gnip4j-core-2.1.0.jar:na]
[10.100.6.81] out: 	at com.zaubersoftware.gnip4j.api.impl.DefaultGnipStream$GnipHttpConsumer.run(DefaultGnipStream.java:229) ~[gnip4j-core-2.1.0.jar:na]
[10.100.6.81] out: 	at java.lang.Thread.run(Thread.java:745) [na:1.8.0_72]

Because the exception is unexpected, it actually assumes that it is disconnects and immediately tries to reconnect, resulting in some thrashing of the connections.