bpd: use pygst.require() before importing gst
bpd: use pygst.require() before importing gst

A user reports that this fixes BPD on OS X.

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