tests(web-server): add unit test for utf8 chars in basePath

This is based on https://github.com/karma-runner/karma/pull/648
fix(web-server): correct urlRegex in custom handlers

I screwed this during the refactorings in 7255aa69abf4dc5d469567ea2ff648d745ee83c1, so this is just reverting to the original name of the property.