Only set optional Oauth params if they're set in config.

Don't add oauth_callback or oauth_verifier from the oauth config array to paramsToSign unless they are set. This prevents them being duplicated if they are set as parameters for a function in a service description.
Fixed odd indentation

Fixed odd indentation
Disallow sufix matching of IP address as per RFC6265 http://tools.ietf.org/html/rfc6265#section-5.1.3
Merge pull request #356 from Danack/patch-1

Only set optional Oauth params if they're set in config.
Returning `false` if `Guzzle\Http\EntityBody::getContentMd5()` fails Not setting a `Content-MD5` on a command if calculating the Content-MD5 fails via the CommandContentMd5Plugin