Raise dependency management to the top level pom

This change raises all versioning of dependencies to the top level pom
in line with maven best practices.

raven-integration-tests as a result has its pom updated so that it
inherits from the top level pom removing the need to duplicate all the
build plugin configuration.
Use 1.0 version of jmockit enabling tests to run on osx

The previous version of jmockit used 0.999.12 was prior to the change
that enabled on-demand loading of the Java agent on Mac OS X which in its
absence resulted in failures when running `mvn test` on OS X.