Changes for 2-legged OAuth

[rdegnan]

The Factual API (http://developer.factual.com/display/docs/Core+API+-+Oauth) is using 2-legged OAuth, in which the Authorization header contains the oauth_consumer_key and oauth_signature but not the oauth_token parameter. This just makes the token parameters in Oauth_client.access_resource optional so it is possible to generate the correct signature for this api. Also the findlib name of ocurl has changed from "ocurl" to "curl" so this would support the newer version.