Added unit test for nested rules.
Simplifying unit tests and removing redundant variable assignments.
Merge pull request #37 from fubhy/add-nested-rules-test

Added unit test for nested rules.
Added unit tests for RulesExpressionTrait.
Removing redundant use statement.
Simplifying RulesOrTest and fixing typo.
Merge pull request #38 from fubhy/add-trait-test

Added unit tests for RulesExpressionTrait.
Adding 'createRulesExpression' method to @covers block.