Make maven-gpg-plugin ignore detached sig files
Make maven-gpg-plugin ignore detached sig files

This prevents the creation of worthless "foo.asc.asc" files when
building signed release artifacts multiple times in succession without
an intervening `mvn clean`.

anuragkh/titan,wangbf/titan,qiuqiyuan/titan,fengshao0907/titan,kalatestimine/titan,CYPP/titan,graben1437/titan,samanalysis/titan,qiuqiyuan/titan,hortonworks/titan,tomersagi/titan,englishtown/titan,kalatestimine/titan,mbrukman/titan,ThiagoGarciaAlves/titan,anuragkh/titan,elkingtonmcb/titan,anuragkh/titan,samanalysis/titan,evanv/titan,twilmes/titan,graben1437/titan,infochimps-forks/titan,CYPP/titan,pluradj/titan,samanalysis/titan,mbrukman/titan,dylanht/titan,anuragkh/titan,evanv/titan,elkingtonmcb/titan,nvoron23/titan,xlcupid/titan,kangkot/titan,ThiagoGarciaAlves/titan,thinkaurelius/titan,tomersagi/titan,qiuqiyuan/titan,qiuqiyuan/titan,nvoron23/titan,jamestyack/titan,kalatestimine/titan,jamestyack/titan,infochimps-forks/titan,wangbf/titan,mbrukman/titan,mwpnava/titan,jamestyack/titan,elubow/titan,jamestyack/titan,evanv/titan,twilmes/titan,mwpnava/titan,samanalysis/titan,wangbf/titan,kangkot/titan,infochimps-forks/titan,xlcupid/titan,nvoron23/titan,anvie/titan,thinkaurelius/titan,jankotek/titan,tomersagi/titan,tomersagi/titan,banjiewen/titan,anvie/titan,infochimps-forks/titan,jankotek/titan,fengshao0907/titan,twilmes/titan,mwpnava/titan,anvie/titan,graben1437/titan,elubow/titan,amcp/titan,wangbf/titan,wangbf/titan,banjiewen/titan,amcp/titan,fengshao0907/titan,xlcupid/titan,xlcupid/titan,evanv/titan,englishtown/titan,elkingtonmcb/titan,hortonworks/titan,englishtown/titan,elubow/titan,anvie/titan,thinkaurelius/titan,pluradj/titan,CYPP/titan,amcp/titan,banjiewen/titan,fengshao0907/titan,dylanht/titan,ThiagoGarciaAlves/titan,kalatestimine/titan,graben1437/titan,amcp/titan,banjiewen/titan,elkingtonmcb/titan,elubow/titan,jankotek/titan,kangkot/titan,mwpnava/titan,mbrukman/titan,kangkot/titan,anvie/titan,elkingtonmcb/titan,tomersagi/titan,evanv/titan,fengshao0907/titan,infochimps-forks/titan,thinkaurelius/titan,anuragkh/titan,kalatestimine/titan,twilmes/titan,ThiagoGarciaAlves/titan,englishtown/titan,pluradj/titan,twilmes/titan,mbrukman/titan,xlcupid/titan,hortonworks/titan,dylanht/titan,jankotek/titan,jankotek/titan,jamestyack/titan,dylanht/titan,hortonworks/titan,pluradj/titan,kangkot/titan,hortonworks/titan,nvoron23/titan,qiuqiyuan/titan,mwpnava/titan,CYPP/titan,ThiagoGarciaAlves/titan