Tests: Fix randomizedtest fail

Closes #79
(cherry picked from commit 3ff4192)
Thread Leak in TwitterStream API

When the river is closed, calling stream.cleanUp() before stream.shutdown() leads to a thread leak: the Dispatcher is never shutdown.

Closes #81
(cherry picked from commit a6a3e5c)
[TESTS] Force deletion of all indices between each test method
(cherry picked from commit aa61107)