SPRINGFIELD — Gov. Bruce Rauner has signed a measure aimed at protecting children and adolescents from lead-contaminated drinking water.Senate Bill 550, approved after a drinking-water crisis in Flint, Mich., made national news and later tests revealed elevated levels of lead in Chicago Public Schools’ water, was vigorously pushed by the Illinois Attorney General’s Office.It mandates day cares and schools that were built before January 2000 and which house pre-kindergarten through fifth grade students …