'Seal' proof of concept; my take on threading issues

So as every one has their proposal to fix threading issues, here's mine.

(It's built on top of a commit of Raoul that is also on other pull-request. The commit is here holding attribution properly and all that.)

This Seal() new method would create a new Request object which would be
the only one allowed to call Please(). This way the parameters it handles
for the request cannot be modified if any thread comes along expecting
to reuse the same object to do a similar call but with different parameters,
like could happen before.

I told the webteam this morning that I would elaborate on this proposal, to also receive the Request in the Please() of FluentApi<T>, however I realised later that it's better that Request class is the only one that has the Please() methods, as is the only one that is immutable.

Let me know what you think!
Thanks