Add tests for BrowseHelper#wikipedia_link
Fixed wikipedia link reference to specific sections

When creating  a wikipedia link from a tag, the function
is (correctly) appending "?userlang=#{I18N.lang}" to the URL,
but doing this breaks the reference to a specific section
of a wikipedia article (if there is any).

For example, if the tag is "wikipedia=Article#Section", the function
would create a link to "../Article#Section?uselang=xx", and then the
browser wouldn't be able to correctly find the section. The correct
link result should be "../Article?uselang=xx#Section".

This commit fixes this by verifying if there is a reference to a
specific section of the article, and then putting "?uselang=#{I18N.lang}"
between the article's name and the section name.