core: Enable DocsServletTest

Removed the @Ignore annotation from DocsServletTest.

Since DocsServlet has changed quite a bit since this test was
introduced, some of the test methods had to be fixed to handle the
different behavior.
Where this posed too much work, the methods were simply removed.

Change-Id: I6e309b7901cada6739ad53efa6d4b1e9c324950d
Signed-off-by: Allon Mureinik <amureini@redhat.com>