How obsessed have schools become in preparing young kids to take tests and achieve in academics? This much: Tutors for kindergarteners — and preschoolers — have become commonplace, the Washington Post reports. You might think this is something that would be popular in New York City or Washington D.C. But go to Clay County, Missouri, and you can find plenty of folks willing to help bring kindergarteners who may already be behind in their studies up to speed — for a price…