Only set optional Oauth params if they're set in config.
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.
wherefortravel/guzzle,lahmizzar/guzzle,mrm/guzzle,videni/guzzle,rsauvatinet/guzzle3,rajaehtesham/guzzle,javierTerry/guzzle,phlogisticfugu/guzzle,justincy/guzzle,EdgarPE/guzzle,mustafavelioglu/guzzle,BostjanOb/guzzle,stea4lth/guzzle,duyhuynhngoc/guzzle,mikicaivosevic/guzzle,Briareos/guzzle,WebSeed/guzzle,kminh/guzzle3,thinsoldier/guzzle,guzzle/guzzle,vrkansagara/guzzle,dshafik/guzzle,staylor/guzzle,sahat/guzzle,Rinat-wc/guzzle,dawehner/guzzle,nazo/guzzle,thinsoldier/guzzle,sulfo/guzzle,chengky/guzzle,paveljanda/guzzle,legovaer/guzzle3,SharpSpring/guzzle3,kminh/guzzle3,WebSeed/guzzle,Tobion/guzzle,phlogisticfugu/guzzle,sulfo/guzzle,paveljanda/guzzle,Naktibalda/guzzle,checat/guzzle,Rinat-wc/guzzle,checat/guzzle,Naktibalda/guzzle,mortenhauberg/guzzle,Tobion/guzzle,EdgarPE/guzzle,Tony133/guzzle,mubassirhayat/guzzle,mortenhauberg/guzzle,Brunty/guzzle,jeskew/guzzle,Tony133/guzzle,kkopachev/guzzle,BostjanOb/guzzle,guzzle/guzzle3,chengky/guzzle,mikicaivosevic/guzzle,lahmizzar/guzzle,atrauzzi/guzzle,hussainweb/guzzle,roundpartner/guzzle3,rsauvatinet/guzzle3,dshafik/guzzle,stea4lth/guzzle,cenxun/guzzle,guzzle/guzzle,cenxun/guzzle,guzzle/guzzle3,SharpSpring/guzzle3,ehough/guzzle,duyhuynhngoc/guzzle,kkopachev/guzzle,dawehner/guzzle,wherefortravel/guzzle,mustafavelioglu/guzzle,legovaer/guzzle3,mrm/guzzle,videni/guzzle,rajaehtesham/guzzle,wulftone/guzzle,justincy/guzzle,roundpartner/guzzle3,atrauzzi/guzzle,barryvdh/guzzle3,ehough/guzzle,hussainweb/guzzle,stefanruijsenaars/guzzle,grokify/guzzle,grokify/guzzle,staylor/guzzle,Brunty/guzzle,dawehner/guzzle,wulftone/guzzle,barryvdh/guzzle3,michabbb-backup/guzzle,Briareos/guzzle,javierTerry/guzzle,jabong/guzzle3,vrkansagara/guzzle,jabong/guzzle3,stefanruijsenaars/guzzle,nazo/guzzle,jeskew/guzzle,michabbb-backup/guzzle