MULE-6485: useContinuations parameter failure

- Fixed the use of Jetty continuations. Reincluded some ignored tests and added new ones.
(cherry picked from commit ceec869ba075fe9ea22396d13039cc8f5ae01a28)

MULE-6485: useContinuations parameter failure

- Fixed schema versions and added constructor to test case.
(cherry picked from commit 42e684217646263859fc0c565cff6f6f86d6e3e9)

MULE-6485: useContinuations parameter failure

- Fixed schema versions.
(cherry picked from commit 33cb660a108c302e6449d762f3f3c246a538c01f)