Upgrade JUnit to 4.11 again

Change I4359067a downgraded JUnit to 4.10 because the index tests
for gerrit-review's backend use some of the basic testing library
in Gerrit and was unable to upgrade to JUnit 4.11.

According to Dave Borowitz's comment on [1], it is now possible to
upgrade to JUnit 4.11 again.

JUnit used to come bundled with hamcrest, but this is no longer the
case starting with 4.11, so we need to expose the hamcrest as well,
because some of the acceptance tests rely on hamcrest being exposed
via the JUnit dependency.

This reverts commit 29c7028495630edeedd99e9a7d053633643971f2.

[1] https://gerrit-review.googlesource.com/#/c/68551/

Change-Id: I7f501f4b6a8f600f372f5ee62f0713170bc474fb