User story
As a Java developer, I can only use JUnit 4 concepts (e.g. Rules) to write Process Engine tests.

Background
The Process Engine test suite uses a mix of JUnit 3 and JUnit 4 concepts in it's tests (inheritance and rules). This should be consolidated and the JUnit 3 concepts removed.

AC

• The Process Engine tests use only JUnit 4 Rules.
• The Concurrency tests helper methods and classes (contained in the ConcurrencyTestHelper class) are provided as a JUnit 4 Rule.
• The Engine Plugin modules (connect-plugin, spin-plugin, identity-ldap) use the Process Engine JUnit 4 Rule classes in their tests.