Fix search query: filter out w3schools by url

To filter out w3schools adequately, "-inurl:w3schools.com" should be used instead of simply "-w3schools". Likely you meant to block the url, not all websites referring to w3school in their content. Like w3fools.com...

Example:

query: w3fools -w3schools
result: w3fools.com is filtered out (not what you want)

query: w3fools -inurl:w3schools.com
result: w3fools.com is the first result

Note: not tested against all available search engines, obviously. It works for Google, Yahoo and Bing, for starters.
Merge pull request #62 from bartvanandel/patch-1

Fix search query: filter out w3schools by url