fix an issue mocking classes w/ traits

if a trait's method declaration fell at the wrong line number, it'd
cause a syntax error, due to the random injection of the transformer

note that this didn't always happen, because of the way the strpos/
substr seek works — it only happened when a trait's method's line
number appeared in an appropriate place in the parent class

methods from traits show the same class name as the including class:
https://bugs.php.net/bug.php?id=64963
http://mouf-php.com/blog/php_reflection_api_traits

closes Codeception/AspectMock#12
add test for bugfix in Codeception/AspectMock#17

as i dive deeper into this, this is probably also a bug in
php-token-reflection, but it seems that project isn't getting much
attention, so it'd be really nice to work around it here
Merge pull request #17 from andyfowler/traits-fix

Fix an issue mocking classes w/ traits