fix: always override specFilter if query exists

[saschanaz]

Retries #24

The previous PR had two problems:

1. Incorrect to check config.specFilter as it's always undefined because config is our own configuration object rather than jasmine global one.
2. Incorrect to check existence of specFilter as even the jasmine global configuration always have specFilter which always returns true.

I think adding a query means the user wants to override the existing filter, so maybe better to do this way.

[dfederm]

Published 1.4.2