chore(badge): add maven central badge with latest version to README
chore(engine): disallow camunda:outputParameter on endEvents

related to #CAM-2400
chore(ProcessEngineRule): replace deprecated TestWatchman super class

TestWatchman is deprecated since JUnit 4.9. ProcessEngineRule therefore
did not support RuleChain. This commit fixes the problem by using the
new type TestWatcher as a super class.

Signed-off-by: Franziska Sauerwein <franziska.sauerwein@gmail.com>
Signed-off-by: Fabian Knittel <fabian.knittel@lettink.de>

related to #CAM-2820
chore(engine): adjust ProcessEngineRule javadoc

related to #CAM-2820
fix(engine): persist form variable on async start event

related to CAM-2636
test(engine): correct test assertions

related to CAM-2636
chore(distro): rename patch scripts to contain version info

Note: This will break the concatenation of the patch script in the pom
if a patch version with to digits (e.g. 7.1.10_to_7.1.11) is released.
In this case the ordering will be wrong because 7.1.10_to_7.1.11 will
be added in front of 7.1.4_to_7.1.5.

related to #CAM-2662