Feature/yaml parsing switch

[ehealy]

@Tapjoy/eng-group-ops

This drives a wedge into the current top level tass commands that allows us to make calls to cloudformation once we've generated valid stack request json/hash (work to be completed in later tasks).

The following tests were succesfull in my local dev environemnt and can be performed using the example yaml files attached:

bundle exec tass scale -f ~/projects/.tass/config/clusters/v1_nonsense_cluster.yaml 
bundle exec tass audit -f ~/projects/.tass/config/clusters/v2_nonsense_cluster.yaml 
bundle exec tass audit -f ~/projects/.tass/config/clusters/v1_nonsense_cluster.yaml 
bundle exec tass create -f ~/projects/.tass/config/clusters/v1_nonsense_cluster.yaml 
bundle exec tass create -f ~/projects/.tass/config/clusters/v2_nonsense_cluster.yaml 
bundle exec tass update -f ~/projects/.tass/config/clusters/v2_nonsense_cluster.yaml 
bundle exec tass update -f ~/projects/.tass/config/clusters/v1_nonsense_cluster.yaml 

[atayarani]

There's probably some cleanup to do down the road, but this is a good start

[ehealy]

@atayarani specs are now inert and will not interact with AWS.

[atayarani]

amazing thanks

[atayarani]

I like how easy the fix makes it look. lgtm

[ehealy]

@atayarani revised to make version implicit vs. explicit.

[atayarani]

lgtm