Parse headers that contain '=' correctly
Parse headers that contain '=' correctly

When using $request->getHeader('Link')->getLink('next') and the URL
contains an '=' (ie, ?page=2), the =2 part was being dropped because of
the explode on '=' on all elements after the explode on ';'.

Key=value pairs are only expected AFTER the ';', so this commit ensures
that this is honoured.

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