* lambda-responses: add method to dispatch concurrency calls
* lambda-resources: add route to handle concurrency requests
* lambda-model: implement put_function_concurrency and concurrency attribute
* put-concurrency-tests: add one simple test
* get_function: add concurrency entry - with test
* lambda-reserved-concurrency: cloudformation support
* lambda-concurrency: implement delete_reserved with tests
* lambda-concurrency: implement get_reserved with tests
* lint
* implementation-cov: mark delete_function_concurrency, put_function_concurrency and get_function_concurrency
* botocore doesn't display concurrency entry for lambdas without it
* lambda(refactor): improvements on response's handler