Oauth support

Warning: I am a Perl Developer so my PHP code may be shitty! :-)

Second warning: I am sitting opposite a certain Mr Gary Gale right now! ;-)

We needed the higher request rate that the oAuth implementation provides, so I added it. Mostly copied:

http://developer.yahoo.com/boss/search/boss_api_guide/codeexamples.html

Hence why I replaced the file_get_contents() with curl_exec()

- Alex