Disable network connectivity in unit tests

[bedrin]

http://stackoverflow.com/questions/28397007/how-to-simulate-lack-of-network-connectivity-in-unit-testing
http://stackoverflow.com/questions/4893129/disable-network-connection
http://stackoverflow.com/questions/4625093/block-outgoing-connections-to-an-ip-for-fail-testing
http://stackoverflow.com/questions/1188530/how-to-simulate-different-network-scenarios-in-java
http://stackoverflow.com/questions/8629252/how-to-simulate-java-socket-connection-break
http://stackoverflow.com/questions/11038544/simulate-network-latency-with-apache-tomcat

[bedrin]

Implemented in 3.1.3