heat engine : Implement Count property for WaitCondition

The Count property of WaitCondition is currently ignored, so
regardless of the number specified the WaitCondition resource will
always go to CREATE_COMPLETE on the first WaitConditionHandle signal.
This patch fixes this so the Count property is handled correctly.

fixes bug 1097813

Change-Id: I71348c553702c0282a8826488c953ac3c2c76e38
Signed-off-by: Steven Hardy <shardy@redhat.com>