Bugfixes and a dockerfile

Various bug fixes related to edge cases in formatting yaml templates

Fix issue awslabs#72 to quote \r newline

Fixed AWS::NoValue issue awslabs#69
Added multibyte character support.
do not change !Join to !Sub if conditional may be AWS::Value

Improve format detection, error reporting, and add input/output overr…

…ide flags

Update README

Fix dependency pinning

Add better support for long strings

Pin dependencies and add snap package support

Fix awslabs#44

Fix quoting of 0-prefixed strings