Overrode sendTerminationNotification() method in
CloudFormationChaosMonkey class to enable email notifications when
no-suffix group names are used.

Modified BasicChaosMonkey and BasicChaosEmailNotifier classes to enable
global email notifications. eg.
simianarmy.chaos.notification.global.receiverEmail = test@email.com
is used to enable global email notifications. Added corresponding unit
test.

Refactored TestChaosMonkeyContext to remove duplicate code