Update Maven GPG plugin from 1.4 to 1.5.
Update Maven GPG plugin from 1.4 to 1.5.

Just to keep up-to-date. Release notes: http://jira.codehaus.org/browse/MGPG/fixforversion/17635
laercioferracini/junit,UnimibSoftEngCourse1516/lab2-es3-s.ravetta,chrisvest/junit,edwardmlyte/junit,mekwin87/junit4,kobe73er/MyUnit,remus32/junit,kobe73er/MyUnit,MingxuanChen/junit,stefanbirkner/junit,UnimibSoftEngCourse1516/lab2-es3-s.ravetta,cherryleer/junit,MichaelJY91/junit,UnimibSoftEngCourse1516/lab2-es3-f.spinardi,AxelMonroyX/junit4,kobe73er/dUnit,sposam/junit,adko-pl/junit,rwarren14/junit,cherryleer/junit,Thothius/junit,y-kt/junit,UnimibSoftEngCourse1516/lab2-es3-f.cirelli1,yusuke/junit,eamonnmcmanus/junit,yusuke/junit,janocat/junit,alb-i986/junit,mnk/junit,slezier/junit,UnimibSoftEngCourse1516/lab2-es3-f.giannini3,schauder/junit,julien-sobczak/junit,UnimibSoftEngCourse1516/lab2-es3-e.nani1,jordancheah/junit,Siddartha07/junit,sposam/junit,laercioferracini/junit,Thothius/junit,ashleyfrieze/junit,jhfjhfj1/junit,laercioferracini/junit,slezier/junit,moinuddin14/junit,mekwin87/junit4,kcooney/junit,dvberkel/junit,openhardnudd/junit,Thothius/junit,UnimibSoftEngCourse1516/lab2-es3-l.salvestrini,ashleyfrieze/junit,jhfjhfj1/junit,junit-team/junit,hansjoachim/junit,julien-sobczak/junit,edwardmlyte/junit,mekwin87/junit4,rwarren14/junit,marcphilipp/junit,powazny/junit4,songfj/junit,elijah513/junit,adko-pl/junit,MichaelJY91/junit,UnimibSoftEngCourse1516/lab2-es3-a.mosini,UnimibSoftEngCourse1516/lab2-es3-f.spinardi,kcooney/junit,0359xiaodong/junit,dvberkel/junit,AxelMonroyX/junit4,GeeChao/junit,VikingDen/junit,flomotlik/junit,hhariri/junit,easyMan-zzy/junit,UnimibSoftEngCourse1516/lab2-es3-o.sertori,UnimibSoftEngCourse1516/lab2-es3-s.renzo,UnimibSoftEngCourse1516/lab2-es3-m.scarpone,schauder/junit,junit-team/junit4,UnimibSoftEngCourse1516/lab2-es3-i.pigazzini,UnimibSoftEngCourse1516/lab2-es3-i.pigazzini,flomotlik/junit,UnimibSoftEngCourse1516/lab2-es3-f.cirelli1,larrychen1990/junit,UnimibSoftEngCourse1516/lab2-es3-l.salvestrini,openhardnudd/junit,alohageck0/junit,1234-/junit,sposam/junit,avandeursen/junit,UnimibSoftEngCourse1516/lab2-es3-i.pigazzini,schauder/junit,onesfreedom/junit,UnimibSoftEngCourse1516/lab2-es3-m.scarpone,JoaquinSiabra/junit,GeeChao/junit,janocat/junit,paulduffin/junit,panchenko/junit,hansjoachim/junit,VikingDen/junit,hhariri/junit,UnimibSoftEngCourse1516/lab2-es3-a.tundo,eamonnmcmanus/junit,hansjoachim/junit,adko-pl/junit,cherryleer/junit,quentin9696/junit,kobe73er/MyUnit,UnimibSoftEngCourse1516/lab2-es3-m.polonioli,UnimibSoftEngCourse1516/lab2-es3-m.vella6,moinuddin14/junit,UnimibSoftEngCourse1516/lab2-es3-f.cirelli1,janocat/junit,avandeursen/junit,baev/junit,elijah513/junit,UnimibSoftEngCourse1516/lab2-es3-m.scarpone,VikingDen/junit,larrychen1990/junit,UnimibSoftEngCourse1516/lab2-es3-a.tundo,UnimibSoftEngCourse1516/lab2-es3-a.tundo,AxelMonroyX/junit4,easyMan-zzy/junit,freezhan/junit,UnimibSoftEngCourse1516/lab2-es3-a.mosini,feisuo/junit,freezhan/junit,powazny/junit4,onesfreedom/junit,witcxc/junit,yusuke/junit,stefanbirkner/junit,UnimibSoftEngCourse1516/lab2-es3-o.sertori,remus32/junit,eamonnmcmanus/junit,UnimibSoftEngCourse1516/lab2-es3-m.polonioli,openhardnudd/junit,kobe73er/dUnit,songfj/junit,jordancheah/junit,edwardmlyte/junit,Clairebi/JUnit-Clone,jordancheah/junit,MichaelJY91/junit,baev/junit,UnimibSoftEngCourse1516/lab2-es3-e.nani1,alohageck0/junit,Clairebi/JUnit-Clone,0359xiaodong/junit,slezier/junit,kobe73er/dUnit,panchenko/junit,1234-/junit,powazny/junit4,rwarren14/junit,smayoorans/junit,songfj/junit,UnimibSoftEngCourse1516/lab2-es3-f.giannini3,freezhan/junit,marcphilipp/junit,junit-team/junit,UnimibSoftEngCourse1516/lab2-es3-a.mosini,jhfjhfj1/junit,mnk/junit,GeeChao/junit,dvberkel/junit,julien-sobczak/junit,junit-team/junit,hhariri/junit,mekwin87/junit4,kcooney/junit,UnimibSoftEngCourse1516/lab2-es3-f.spinardi,UnimibSoftEngCourse1516/lab2-es3-s.ravetta,flomotlik/junit,easyMan-zzy/junit,chrisvest/junit,1234-/junit,alb-i986/junit,chrisvest/junit,UnimibSoftEngCourse1516/lab2-es3-l.salvestrini,UnimibSoftEngCourse1516/lab2-es3-o.sertori,remus32/junit,mnk/junit,larrychen1990/junit,paulduffin/junit,panchenko/junit,UnimibSoftEngCourse1516/lab2-es3-m.vella6,marcphilipp/junit,MingxuanChen/junit,UnimibSoftEngCourse1516/lab2-es3-s.renzo,y-kt/junit,feisuo/junit,0359xiaodong/junit,Siddartha07/junit,moinuddin14/junit,stefanbirkner/junit,baev/junit,UnimibSoftEngCourse1516/lab2-es3-m.polonioli,Clairebi/JUnit-Clone,JoaquinSiabra/junit,alohageck0/junit,UnimibSoftEngCourse1516/lab2-es3-s.renzo,witcxc/junit,junit-team/junit4,avandeursen/junit,UnimibSoftEngCourse1516/lab2-es3-f.giannini3,MingxuanChen/junit,quentin9696/junit,alb-i986/junit,quentin9696/junit,smayoorans/junit,ashleyfrieze/junit,onesfreedom/junit,junit-team/junit4,paulduffin/junit,UnimibSoftEngCourse1516/lab2-es3-m.vella6,elijah513/junit,feisuo/junit,witcxc/junit,JoaquinSiabra/junit,y-kt/junit,smayoorans/junit,Siddartha07/junit,UnimibSoftEngCourse1516/lab2-es3-e.nani1