Switched curl_exec() for class.geoservice.php

Using OAuth.php's OAuthUtil::build_http_query() function, and
php5-curl's curl_init() and curl_exec() functions, to do the web calls
in class.geoservice.php

This is the first step in enabling full OAuth support following the
examples given in
http://developer.yahoo.com/boss/search/boss_api_guide/codeexamples.html
Added support for oAuth for YQL lookups

oAuth is automatically enabled when the cc_key and cc_secret keys are
set to something in the config.ini config file.

When enabled oAuth mode causes class.geoservice.php to alter which end
point URL it uses, and also adds the appropriate oAuth headers to the
HTTP request.

Finally, because the rate limits on the oAuth API are much looser than
on the non-oAuth API, the webServiceWait variable is reduced from 0.5
seconds to 0.2 seconds. Note: this does have the danger of hitting the
100K/day limit, but keeps within the 20K/hour per IP limit.
Removed "YQL oAuth implementation" from TODO list
Merge pull request #4 from kaoru/oauth-support

Oauth support for YQL