Implemented test case that demonstrates how it could work, currently failing.
Reverted changes to createCondition(), not needed.
Implemented Rules State handling and moved rules expression interface to all use rules expressions.
Moved the empty summary default for test condition plugins out of the base class.
Fixed typos in comments.
Fixed invocation of phpunit in Travis CI test suite.
Merge pull request #68 from klausi/travis-phpunit-fail

Fix invocation of phpunit in Travis CI test suite.
Initial commit of 'Data is empty' condition with unit test.