change PropertyMap in kinesisanalyticsv2 PropertyGroup to dict

[m-architek]

This PR fixing bug in field definition of PropertyGroup in kinesisanalyticsv2 module.

Reference:
https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-properties-kinesisanalyticsv2-application-propertygroup.html

CF type is Json, bu json_checker represents String with json content. Correct type in troposphere to represent CF Json type is dict.

For example, in code pipeline Action CF:
https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-properties-codepipeline-pipeline-stages-actions.html
Configuration field is of type Json, so in troposphere:
https://github.com/cloudtools/troposphere/blob/master/troposphere/codepipeline.py
field type is dict, what is correct.

I tested this change in my project using version from my fork and it works correctly.

[markpeek]

Thanks! I added a fix for the tests to pass as well.