setup.py: remove namespace_packages declaration
setup.py: remove namespace_packages declaration

Looks like the Setuptools people are moving to make this an error. I don't
think it was doing anything anyway.

https://bitbucket.org/pypa/setuptools/issue/12/update-or-remove-warning-when-namespace

shamangeorge/beets,arabenjamin/beets,LordSputnik/beets,PierreRust/beets,tima/beets,xsteadfastx/beets,mosesfistos1/beetbox,Andypsamp/CODjunit,imsparsh/beets,Freso/beets,mathstuf/beets,sadatay/beets,bj-yinyan/beets,drm00/beets,PierreRust/beets,beetbox/beets,artemutin/beets,tima/beets,artemutin/beets,diego-plan9/beets,lengtche/beets,ibmibmibm/beets,lightwang1/beets,shamangeorge/beets,jmwatte/beets,Kraymer/beets,parapente/beets,Wen777/beets,xsteadfastx/beets,ttsda/beets,dfc/beets,jackwilsdon/beets,m-urban/beets,Andypsamp/CODjunit,moodboom/beets,moodboom/beets,untitaker/beets,MyTunesFreeMusic/privacy-policy,kareemallen/beets,lightwang1/beets,MyTunesFreeMusic/privacy-policy,mathstuf/beets,Andypsamp/CODfinalJUNIT,lengtche/beets,parapente/beets,imsparsh/beets,xsteadfastx/beets,kareemallen/beets,marcuskrahl/beets,Freso/beets,mathstuf/beets,parapente/beets,mosesfistos1/beetbox,jcoady9/beets,asteven/beets,LordSputnik/beets,sampsyo/beets,mosesfistos1/beetbox,dfc/beets,ruippeixotog/beets,Andypsamp/CODfinalJUNIT,Andypsamp/CODjunit,dfc/beets,ruippeixotog/beets,swt30/beets,Wen777/beets,moodboom/beets,mosesfistos1/beetbox,madmouser1/beets,ibmibmibm/beets,swt30/beets,xsteadfastx/beets,YetAnotherNerd/beets,shanemikel/beets,ttsda/beets,Kraymer/beets,beetbox/beets,jackwilsdon/beets,sadatay/beets,kelvinhammond/beets,beetbox/beets,swt30/beets,kareemallen/beets,jcoady9/beets,madmouser1/beets,arabenjamin/beets,Kraymer/beets,andremiller/beets,randybias/beets,mried/beets,ibmibmibm/beets,YetAnotherNerd/beets,multikatt/beets,marcuskrahl/beets,mried/beets,multikatt/beets,SusannaMaria/beets,asteven/beets,bj-yinyan/beets,jcoady9/beets,LordSputnik/beets,SusannaMaria/beets,krig/beets,pkess/beets,jmwatte/beets,Dishwishy/beets,SusannaMaria/beets,mried/beets,Andypsamp/CODfinalJUNIT,sampsyo/beets,andremiller/beets,kelvinhammond/beets,diego-plan9/beets,gabrielaraujof/beets,Andypsamp/CODfinalJUNIT,lightwang1/beets,arabenjamin/beets,jackwilsdon/beets,MyTunesFreeMusic/privacy-policy,kareemallen/beets,bj-yinyan/beets,shamangeorge/beets,lightwang1/beets,moodboom/beets,swt30/beets,diego-plan9/beets,ttsda/beets,Freso/beets,LordSputnik/beets,artemutin/beets,madmouser1/beets,randybias/beets,multikatt/beets,jcoady9/beets,jackwilsdon/beets,parapente/beets,Kraymer/beets,drm00/beets,MyTunesFreeMusic/privacy-policy,gabrielaraujof/beets,untitaker/beets,ruippeixotog/beets,imsparsh/beets,mathstuf/beets,shanemikel/beets,Dishwishy/beets,m-urban/beets,m-urban/beets,drm00/beets,ibmibmibm/beets,PierreRust/beets,pkess/beets,kelvinhammond/beets,drm00/beets,YetAnotherNerd/beets,shanemikel/beets,krig/beets,SusannaMaria/beets,mried/beets,bj-yinyan/beets,lengtche/beets,shanemikel/beets,Andypsamp/CODfinalJUNIT,ttsda/beets,gabrielaraujof/beets,madmouser1/beets,Andypsamp/CODjunit,andremiller/beets,pkess/beets,asteven/beets,krig/beets,imsparsh/beets,Dishwishy/beets,multikatt/beets,sampsyo/beets,Dishwishy/beets,m-urban/beets,randybias/beets,lengtche/beets,tima/beets,sadatay/beets,tima/beets,untitaker/beets,asteven/beets,ruippeixotog/beets,artemutin/beets,shamangeorge/beets,diego-plan9/beets,randybias/beets,arabenjamin/beets,beetbox/beets,marcuskrahl/beets,Freso/beets,sampsyo/beets,jmwatte/beets,untitaker/beets,PierreRust/beets,dfc/beets,pkess/beets,Wen777/beets,Andypsamp/CODjunit,jmwatte/beets,gabrielaraujof/beets,sadatay/beets,YetAnotherNerd/beets,marcuskrahl/beets,kelvinhammond/beets