Allow on/off switch for all activity notifications.

Allow on/off switch for all activity notifications.

Default behaviour was/is to do all actitivity notifications supported by plugin.
Configure is in the config file by passing array with keyed boolean values like:

addPlugin('Activity', array(
			    'StartFollowUser' => true,
			    'StopFollowUser' => false,
			    'JoinGroup' => true,
			    'LeaveGroup' => true,
			    'StartLike' => true,
			    'StopLike' => false));