Description:
------------
Sending an OAuth request to php-fpm 7.0.5 with oauth 2.0.1dev (git 5fb568c) on nginx 1.8.1 always fails with the following error:

> oauth_problem=parameter_absent

This happens although the HTTP_AUTHORIZATION $_SERVER variable contains the correct Authentication header line.

Calling the test script with curl and some oauth headers yields a signature_invalid message if all works fine, and the described parameter_absent error on my nginx test host.

Test script:
---------------
<?php
try {
    var_dump($_SERVER['HTTP_AUTHORIZATION']);
    $provider = new OAuthProvider();
    $provider->isRequestTokenEndpoint(true);
    $provider->consumerHandler(function(){return OAUTH_OK;});
    $provider->timestampNonceHandler(function(){return OAUTH_OK;});
    $provider->checkOAuthRequest();
} catch (OAuthException $e) {
    header('HTTP/1.0 400 Bad Request');
    echo OAuthProvider::reportProblem($e);
    exit(2);
}


Expected result:
----------------
$ curl -H 'Authorization: OAuth realm="test",oauth_consumer_key="test",oauth_nonce="test",oauth_signature="test",oauth_signature_method="HMAC-SHA1",oauth_timestamp="1",oauth_token="test",oauth_version="1.0"' http://localhost/server.php

oauth_problem=signature_invalid&debug_sbs=GET&http%3A%2F%2Flocalhost%2Fserver.php&oauth_consumer_key%3Dtest%26oauth_nonce%3Dtest%26oauth_signature_method%3DHMAC-SHA1%26oauth_timestamp%3D1%26oauth_token%3Dtest%26oauth_version%3D1.0


Actual result:
--------------
$ curl -H 'Authorization: OAuth realm="test",oauth_consumer_key="test",oauth_nonce="test",oauth_signature="test",oauth_signature_method="HMAC-SHA1",oauth_timestamp="1",oauth_token="test",oauth_version="1.0"' http://localhost:8080/server.php

string(180) "OAuth realm="test",oauth_consumer_key="test",oauth_nonce="test",oauth_signature="test",oauth_signature_method="HMAC-SHA1",oauth_timestamp="1",oauth_token="test",oauth_version="1.0""

oauth_problem=parameter_absent&oauth_parameters_absent=oauth_consumer_key%26oauth_signature%26oauth_signature_method%26oauth_nonce%26oauth_timestamp