Check search limit depth with an inequality

Otherwise, when we check for equality, the test fails if the search start beneath
the max depth.
Eg: if I have the page ns1:ns2:mypage in my wiki, and launch the xmlrpc query
getPagelist("ns1", "depth => 1"), without this patch, it retrieves mypage
If depth option is set to 0, we should recurse forever

At least if we want to be consistent with search_universal
Merge pull request #154 from gturri/searchDepth

Check search limit depth with an inequality