Build weasyprint for python 3.6 to run on aws lambda.

1. make build-package
2. cp samples/handler.py /build/package/task
3. make zip-package
4. Upload the resulting package weasy-lambda/build/package/task.zip to lambda
5. Configure function to use handler.handler as the lambda handler
6. Set execution timeout to 10

1. make build-package
2. Add your custom lambda handler to weasy-lambda/build/package/task or use the sample in weasy-lambda/samples/handler.py
3. make zip-package
4. Upload the resulting package weasy-lambda/build/package/task.zip to lambda

1. make build-layer
2. make zip-layer
3. Use the resulting package weasy-lambda/build/layer/python.zip to create a new lambda layer