Fix album import feed with slashes
Fix album import feed with slashes

Makes tests from f2da1922b28571216c7bc0eaa71f56a316dc0d5d pass.
Fixes #610 and supersedes #611.

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