Add SqsBatchResponse to static events

[jamescoleuk]

Resolves #94

• Adds SqsBatchResponse to static events.
• Removes from generated events.
• Add serialization/deserialization test.
• Uses test data taken from an AWS example.
• cargo build/check/test pass.

I did not test code generation. I installed Go but don't know how to make $GOPATH/src/github.com/aws/aws-lambda-go exist. I believe it is go install but go install github.com/aws/aws-lambda-go@latest failed:

go: downloading github.com/aws/aws-lambda-go v1.31.1
go: github.com/aws/aws-lambda-go@latest: module github.com/aws/aws-lambda-go@latest found (v1.31.1), but does not contain package github.com/aws/aws-lambda-go

[calavera]

There is just one thing missing. Don't worry about the Go bindings, you don't need to do that.