Added getLookupValues, this will do getAllLookupValues as well, you can omit the second argument for all, or just provide a '*' as the second argument.
Added a connected variable so you won't connect twice / disconnect when not connected. Moved some header checks here because they aren't cURL specific.
Added disconnect method
Allow null in constructor so you don't have to pass a response. This isn't really necessary for things like LookupResults because the parent has the response, although we may want to pass it. Won't really use much memory I think
For GetMetadata requests.
Custom exceptions
Todo..