[ticket/14442] Use Goutte 2.0 for functional tests
* marc1706/ticket/14442:
[ticket/14442] Use get_content() in functional test case
[ticket/14442] Properly set plupload header
[ticket/14442] Use get_content() in plupload functional tests
[ticket/14442] Use Goutte 2.0 instead of outdated 1.0