Add CloudFormation utility functions

This adds some general-purpose functions to create or update an AWS CloudFormation stack from a JSON template file.
Purely stylistically/conventionally, in Python a double quote `"` is used, as a rough convention, for "textual" / human language strings, vs. single quotes `'` are used for identifier/keyword-like strings, e.g. `data_type = 'int'`.  Does that distinction make sense?

Thus for example I think conventionally it's pretty rare to see multi-line strings with single-quote, it kind of doesn't make sense as those kinds of strings are usually human-textual stuff.