Allow using strict HTTP verbs instead of LIST

[toomai]

Vault default to LIST HTTP verbs which is not (yet ?) RFC compliant and can cause problems in some setups. I propose a new settings, defaulting to false. This will trigger request transformation and switch to GET request with the list=true query parameter.

Saw one referenced issue #109. I saw the decision was taken to use GET request all the time but this has been ready for a long time on my side. I just forgot to PR it, let me know if you still plan on using GET.

I also have another feature on a different branch to add the ListIssuer and ListIssuerCrl calls, let me know if you'd be interested to merge these too.

[stormshield-gt]

Thanks for opening a PR !

I like the idea of handling this with middleware rather than having to distinct requests for LIST and GET with list=true.

I want to explore a little bit with #105 and see I can directly generate list=true for all list endpoints instead of adding them to remove them latter. But if the need is really urgent, I don't mind adding this setting for now.

I also have another feature on a different branch to add the ListIssuer and ListIssuerCrl calls, let me know if you'd be interested to merge these too.

Any contributions are welcomed! If you do so, please add some tests to the PR