Upgrade to JMock 2.6.0 RC2

We need JMock 2.6.0 and the final is not available but we should still upgrade because ATM we cannot have several @RunWith and JMock is using one to verify if expectations have been met at end of tests. And we also need @RunWith for our custom suites...

JMock 2.6 fixes this with http://svn.codehaus.org/jmock/trunk/jmock2/src/org/jmock/integration/junit4/JUnitRuleMockery.java

And a few other things like:

• a new auto-mocking functionality that reduces boilerplate code
• support for testing multitheaded code
• a Mockery that works with JUnit's rules mechanism (that's JUnitRuleMockery)
• better failure diagnostics.

See:

• Release notes for 2.6.0RC2: http://jira.codehaus.org/secure/ReleaseNote.jspa?projectId=10336&version=14409
• Release notes for 2.6.0RC1: http://jira.codehaus.org/secure/ReleaseNote.jspa?projectId=10336&styleName=Html&version=14409

The only downside of JMock 2.6 is a behavior change for matching null which can be considered a regression, see http://jira.codehaus.org/browse/JMOCK-261

However the workaround described in the issue is pretty simple and I think acceptable for now.