Improve post limiting

[rferreira]

Follow along what tomcat does and implement a max-swallow-size to limi the number of bytes discarded. https://medium.com/@priyammgupta/tomcat-server-request-size-d5e8807a990c

[rferreira]

We should also handle expect continue differently and ensure that if the content length is available we fail the preflight request. Tomcat seems to not do that