Pin dependencies and add snap package support

Fix awslabs#44

Fix quoting of 0-prefixed strings

A few bugfixes

Refactor into discrete packages, paving the way for greater things. A…

…dded support for long-form yaml and better clean-up of nested values.

Format flags, no-flip flag, and nested cleans.

Fixed a number of bugs with GetAtt and Join

More fixes to GetAtt handling and the custom yaml loader/dumper

No change. Pypi versioning issue.

Fix GetAtt handling