Add support for REQUEST type Lambda Authorizers

[tommie-lie]

Description

Support for REQUEST authorizers was almost there, as the type authorizer property was mostly passed through to the CloudFormation templates. This PR extends the handler middleware to also treat events of type REQUEST as authorization events. It also extends the template creation to treat TOKEN and REQUEST type authorizers equal (defaulting to TOKEN just as before).
The most significant change is in the logic how the authorization type for API routes is derived from the authorizer type: Instead of assuming CUSTOM if the type is not specified, the authorizer type correctly defaults to TOKEN. The authorization type is then mapped to CUSTOM for both, TOKEN and REQUEST authorizers.

Added unit tests and tested on live environments on AWS.

GitHub Issues

Fixes #1159

[coveralls]

Coverage increased (+0.02%) to 72.982% when pulling 3c877d3 on tommie-lie:feature/request-authorizer into 80a6881 on Miserlou:master.

[rodriguesgm]

Any news on this? thanks

[mcbridet]

I'd love this too, using zappa from this PR at the moment.