Fix support of non-GET (POST, PUT, ...) requests rewriting

[benoit74]

Currently, non-GET (POST, PUT, ...) requests returning an HTML document are supposed to work but they are not tested at all.

It is supposed to work based on what has been transferred from wabac.js, but not tested.

We need to :

• create a real test case on test website
• ensure rewrite works as expected on these requests
• include this non-GET requests dataset in the automated tests