* Allow protection of certain keys during camel_to_snake
Create an `ignore_list` parameter that preserves the case
of the contents of certain dictionaries. Most valuable
for `tags` but other uses might arise.
* Port ec2_vpc_route_table to boto3
Update tests to reflect fixes in boto3.
* Add RETURN documentation to ec2_vpc_route_table
* Update DOCUMENTATION to be valid yaml
* Add check mode tests
