UP-4855: Add gradle signing plugin
UP-4855: Add gradle signing plugin

bjagg/uPortal,GIP-RECIA/esup-uportal,jonathanmtran/uPortal,ChristianMurphy/uPortal,Jasig/uPortal,mgillian/uPortal,GIP-RECIA/esup-uportal,Jasig/uPortal,stalele/uPortal,cousquer/uPortal,phillips1021/uPortal,mgillian/uPortal,phillips1021/uPortal,stalele/uPortal,phillips1021/uPortal,mgillian/uPortal,ChristianMurphy/uPortal,phillips1021/uPortal,GIP-RECIA/esco-portail,GIP-RECIA/esco-portail,groybal/uPortal,Jasig/uPortal,groybal/uPortal,stalele/uPortal,GIP-RECIA/esup-uportal,GIP-RECIA/esup-uportal,groybal/uPortal,bjagg/uPortal,bjagg/uPortal,phillips1021/uPortal,groybal/uPortal,jonathanmtran/uPortal,jonathanmtran/uPortal,stalele/uPortal,ChristianMurphy/uPortal,GIP-RECIA/esup-uportal,cousquer/uPortal,groybal/uPortal,stalele/uPortal,cousquer/uPortal,GIP-RECIA/esco-portail