artresizer: add check_method()
artresizer: add check_method()

for the case where we want to know if a specific method is available

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