Fix build base file name.
Fix build base file name.

We were previously relying on the fact that `projectFilter` was a
string that happened to be the beginning part of the filenames. This
adds the specific value that we need.

zeppelin/emberjs-website,MinxianLi/ember,elidupuis/website,raycohen/website,josemarluedke/ember-website,elwayman02/website,greyhwndz/website,balupton/ember-website,quangv/website,quangv/website,josemarluedke/ember-website,maxcal/website,EricSchank/website,mrjavascript/website,SaladFork/emberjs-website,Eric-Guo/website,SaladFork/emberjs-website,datajohnny/website,josemarluedke/ember-website,datajohnny/website,martndemus/website,tmock12/website,workmanw/ember-website,shearwater-intl/website,mrjavascript/website,AgilionApps/website,datajohnny/website,raycohen/website,kpfefferle/website,SaladFork/emberjs-website,balupton/ember-website,MinxianLi/ember,koriroys/emberjs-website,elwayman02/website,zeppelin/emberjs-website,ktornwall/website,ktornwall/website,bmac/website,davidpett/website,greyhwndz/website,kpfefferle/website,AgilionApps/website,mrjavascript/website,bmac/website,duggiefresh/website,workmanw/ember-website,tmock12/website,raycohen/website,elwayman02/website,shearwater-intl/website,davidpett/website,AaronSikes/website,shearwater-intl/website,cyberkoi/website,wifelette/website,koriroys/emberjs-website,tmock12/website,kpfefferle/website,greyhwndz/website,kkenan/website,quangv/website,josemarluedke/ember-website,cyberkoi/website,AaronSikes/website,workmanw/ember-website,SaladFork/emberjs-website,kkenan/website,bmac/website,davidpett/website,zeppelin/emberjs-website,EricSchank/website,wifelette/website,ktornwall/website,cllns/emberjs-website,cllns/emberjs-website,MinxianLi/ember,AgilionApps/website,martndemus/website,Eric-Guo/website,elidupuis/website,wifelette/website,zeppelin/emberjs-website,duggiefresh/website,balupton/ember-website,elidupuis/website,bmac/website,workmanw/ember-website,duggiefresh/website,kkenan/website,koriroys/emberjs-website,cyberkoi/website,maxcal/website,AaronSikes/website,EricSchank/website,cllns/emberjs-website,Eric-Guo/website,maxcal/website,martndemus/website