New method getCategoryID

Gets eBay's CategoryID based on the code name for the category
Check if $results is empty before returning
Fix typo ($results -> $result) and trim in package_info()
Default $sandbox to false in __construct()
Beginning of UploadSiteHostedPictures Request

Work in progress. Will be difficult, since it is multi-part
Added UploadSiteHostedPictures to $call_list