saml: Add support for signing SP metadata.
saml: Add support for signing SP metadata.

Thanks to Gyula Szabó for providing this patch.

git-svn-id: a243b28a2a52d65555a829a95c8c333076d39ae1@2715 44740490-163a-0410-bde0-09ae8108e29a

sylvainmed/simplesamlphp,grnet/simplesamlphp,dzuelke/simplesamlphp,shoaibali/simplesamlphp,jschlyter/simplesamlphp,BrettMerrick/simplesamlphp,girgen/simplesamlphp,grnet/simplesamlphp,ghalse/simplesamlphp,StudentLifeMarketingAndDesign/simplesamlphp,girgen/simplesamlphp,Kunstmaan/simplesamlphp,dialogik/simplesamlphp,gtkrug/simplesamlphp,cwaldbieser/simplesamlphp,ghalse/simplesamlphp,madmatt/simplesamlphp,sitya/simplesamlphp,simplesamlphp/simplesamlphp,gtkrug/simplesamlphp,dialogik/simplesamlphp,cwaldbieser/simplesamlphp,Kunstmaan/simplesamlphp,simplesamlphp/simplesamlphp,dnmvisser/simplesamlphp,cwaldbieser/simplesamlphp,girgen/simplesamlphp,dnmvisser/simplesamlphp,grnet/simplesamlphp,shoaibali/simplesamlphp,shoaibali/simplesamlphp,dzuelke/simplesamlphp,sylvainmed/simplesamlphp,simplesamlphp/simplesamlphp,madmatt/simplesamlphp,BrettMerrick/simplesamlphp,grnet/simplesamlphp,Kunstmaan/simplesamlphp,sitya/simplesamlphp,shoaibali/simplesamlphp,StudentLifeMarketingAndDesign/simplesamlphp,simplesamlphp/simplesamlphp,Kunstmaan/simplesamlphp,ghalse/simplesamlphp,dialogik/simplesamlphp,madmatt/simplesamlphp,BrettMerrick/simplesamlphp,sylvainmed/simplesamlphp,madmatt/simplesamlphp,StudentLifeMarketingAndDesign/simplesamlphp,maytechnet/simplesamlphp,sylvainmed/simplesamlphp,dzuelke/simplesamlphp,maytechnet/simplesamlphp,girgen/simplesamlphp,dialogik/simplesamlphp,StudentLifeMarketingAndDesign/simplesamlphp,sitya/simplesamlphp,jschlyter/simplesamlphp,maytechnet/simplesamlphp,girgen/simplesamlphp,cwaldbieser/simplesamlphp,dialogik/simplesamlphp,gtkrug/simplesamlphp,BrettMerrick/simplesamlphp,jschlyter/simplesamlphp,ghalse/simplesamlphp,maytechnet/simplesamlphp,jschlyter/simplesamlphp,dnmvisser/simplesamlphp,sitya/simplesamlphp,dnmvisser/simplesamlphp,dzuelke/simplesamlphp,gtkrug/simplesamlphp,jschlyter/simplesamlphp