Update beets/ui/__init__.py
Update beets/ui/__init__.py

Fix for Issue 450: Expand templates in art_filename config option
YetAnotherNerd/beets,madmouser1/beets,Freso/beets,kelvinhammond/beets,m-urban/beets,multikatt/beets,xsteadfastx/beets,pdf/beets,lightwang1/beets,randybias/beets,lengtche/beets,gabrielaraujof/beets,jmwatte/beets,tima/beets,artemutin/beets,beetbox/beets,LordSputnik/beets,sadatay/beets,lightwang1/beets,untitaker/beets,mried/beets,parapente/beets,mried/beets,drm00/beets,tima/beets,arabenjamin/beets,xsteadfastx/beets,Andypsamp/CODjunit,multikatt/beets,LordSputnik/beets,PierreRust/beets,sadatay/beets,arabenjamin/beets,moodboom/beets,Kraymer/beets,SusannaMaria/beets,multikatt/beets,gabrielaraujof/beets,ibmibmibm/beets,bj-yinyan/beets,ttsda/beets,marcuskrahl/beets,mried/beets,swt30/beets,m-urban/beets,imsparsh/beets,Andypsamp/CODfinalJUNIT,LordSputnik/beets,sadatay/beets,Wen777/beets,arabenjamin/beets,jackwilsdon/beets,imsparsh/beets,shamangeorge/beets,gabrielaraujof/beets,kelvinhammond/beets,ibmibmibm/beets,moodboom/beets,diego-plan9/beets,PierreRust/beets,randybias/beets,YetAnotherNerd/beets,mosesfistos1/beetbox,pdf/beets,SusannaMaria/beets,Wen777/beets,krig/beets,jcoady9/beets,parapente/beets,jayme-github/beets,artemutin/beets,diego-plan9/beets,beetbox/beets,untitaker/beets,ruippeixotog/beets,imsparsh/beets,MyTunesFreeMusic/privacy-policy,shamangeorge/beets,mosesfistos1/beetbox,marcuskrahl/beets,sadatay/beets,sampsyo/beets,shamangeorge/beets,ruippeixotog/beets,multikatt/beets,lengtche/beets,drm00/beets,LordSputnik/beets,ttsda/beets,jcoady9/beets,kareemallen/beets,Dishwishy/beets,Freso/beets,parapente/beets,mried/beets,Wen777/beets,lengtche/beets,jbaiter/beets,asteven/beets,jcoady9/beets,ruippeixotog/beets,untitaker/beets,mathstuf/beets,gabrielaraujof/beets,artemutin/beets,Kraymer/beets,untitaker/beets,jcoady9/beets,jmwatte/beets,Freso/beets,Andypsamp/CODjunit,Andypsamp/CODfinalJUNIT,mathstuf/beets,m-urban/beets,pkess/beets,MyTunesFreeMusic/privacy-policy,sampsyo/beets,beetbox/beets,shanemikel/beets,mosesfistos1/beetbox,pkess/beets,dfc/beets,drm00/beets,tima/beets,kareemallen/beets,Kraymer/beets,randybias/beets,Kraymer/beets,madmouser1/beets,Freso/beets,Andypsamp/CODjunit,dfc/beets,xsteadfastx/beets,jackwilsdon/beets,SusannaMaria/beets,andremiller/beets,ttsda/beets,bj-yinyan/beets,Andypsamp/CODjunit,dfc/beets,ttsda/beets,marcuskrahl/beets,lightwang1/beets,MyTunesFreeMusic/privacy-policy,jackwilsdon/beets,bj-yinyan/beets,mosesfistos1/beetbox,YetAnotherNerd/beets,YetAnotherNerd/beets,parapente/beets,shamangeorge/beets,swt30/beets,drm00/beets,asteven/beets,swt30/beets,artemutin/beets,MyTunesFreeMusic/privacy-policy,swt30/beets,jbaiter/beets,pkess/beets,krig/beets,randybias/beets,Dishwishy/beets,Andypsamp/CODfinalJUNIT,ibmibmibm/beets,shanemikel/beets,moodboom/beets,diego-plan9/beets,SusannaMaria/beets,kareemallen/beets,kelvinhammond/beets,beetbox/beets,diego-plan9/beets,lengtche/beets,arabenjamin/beets,madmouser1/beets,m-urban/beets,tima/beets,mathstuf/beets,Andypsamp/CODfinalJUNIT,kareemallen/beets,pkess/beets,imsparsh/beets,xsteadfastx/beets,krig/beets,PierreRust/beets,kelvinhammond/beets,shanemikel/beets,asteven/beets,sampsyo/beets,sampsyo/beets,asteven/beets,Dishwishy/beets,moodboom/beets,marcuskrahl/beets,lightwang1/beets,Andypsamp/CODjunit,madmouser1/beets,shanemikel/beets,ibmibmibm/beets,jmwatte/beets,andremiller/beets,jackwilsdon/beets,jmwatte/beets,dfc/beets,andremiller/beets,ruippeixotog/beets,Andypsamp/CODfinalJUNIT,PierreRust/beets,jayme-github/beets,Dishwishy/beets,bj-yinyan/beets,mathstuf/beets