Memcache: Add delete method.
Memcache: Add delete method.

git-svn-id: a243b28a2a52d65555a829a95c8c333076d39ae1@2489 44740490-163a-0410-bde0-09ae8108e29a

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