Add support for recursive resolving

[martysweet]

Add support for recursive resolving, which allows for Fn::If parameters to be resolved for whole blocks which depend on a Condition, see #106

[martysweet]

@RazzM13 Does this look sane?

[RazzM13]

Hi @martysweet, sorry I've been rather busy lately and I haven't really had the time to take a proper look into this but based on a quick glance, I believe that your solution tackles the problem from a different angle than what I had anticipated. I was under the impression that if Fn::If resolves with AWS::NoValue then the property that contains the intrinsic should be removed, as stated here. Then again, I haven't really had a proper look into this so please ignore if it doesn't make sense.

[martysweet]

Yep so there are two issues here:

1. The successful branch of the IF statement was not being resolved, so its possible to put whole nested chunks of resources in here with more intrinsics, these were being thrown back out on a successful IF but caused issue cause nothing was done to resolve them

2. When a NoValue was set by the user, the return value of the IF statement was undefined, this was passed all the way back and being checked by one of the type checkers, instead of being removed and thus throwing an error. Prehaps removing the item if it's undefined would be better, not sure the best place to put that though.