SLING-3620 - POM preparations for release

Add scm settings

git-svn-id: https://svn.apache.org/repos/asf/sling/trunk@1598531 13f79535-47bb-0310-9956-ffa450edef68
SLING-3615 - it tests in tooling/ide/eclipse-test fail on MacOS due to
missing (default) JRE

Always run the tests on a non-UI thread. Reasons:

- has no functional impact on the tests
- is required by SWTBot, which we are considering using
- allows the Eclipse instance to be interacted with during tests

git-svn-id: https://svn.apache.org/repos/asf/sling/trunk@1598532 13f79535-47bb-0310-9956-ffa450edef68