Support passing stack outputs as input parameters during new stack creation

[weavenet]

• Added --stacks (-s) option to create
• Stack names passed in will have outputs read as inputs for the new stack
• Attributes specified on the CLI will override those passed from outputs
• When multiple stacks return the same output, it is joined as a CSV and passed to parameter

[thbishop]

Waiting on some examples of what this would look like to use :wink:

[weavenet]

Let it be known, that on Feb 13th at 3:00PM PDT @thbishop stated "this would be a great feature to have to assist in building my VPC"

[thbishop]

I think the exact words were "I can see how this could be useful"

[weavenet]

First pass at the reference app for Sir Thomas Bishop

https://gist.github.com/brettweavnet/66fec6d0cc2c830c26c8

[thbishop]

We may want to think about adding some documentation about this feature. Especially the convention it expects, how it handles single/multiple attributes, etc.

[weavenet]

Agree on the documentation, where do you see it going? In the CLI and / or wiki?

[thbishop]

I think more details in the CLI should work for now. If we need to convey a ton of information, then perhaps wiki or maybe an examples directory

[weavenet]

@thbishop can you re-review. I think I hit allt he issues. Can you re-review / comment but not merge till we have a final discussion?

[thbishop]

Added a couple of minor comments. Also, can you merge in the latest from master?

[thbishop]

@brettweavnet Looks good. Just need to pull in latest master updates as it looks like there's a conflict. I think it's probably the CHANGELOG.

[weavenet]

latest master pulled in, clean to merge