Editor's note: Ruben Navarrette Jr. is a CNN.com contributor, a nationally syndicated columnist and an NPR commentator. Notice, I said "the politics" of border security. That means the way both political parties use and manipulate for political benefit what should be top priority: securing our nation's borders.I mean "borders." Plural. Not just the southern one that separates our country from dark-skinned people whom many Americans consider inferior and dangerous.Given what we hear in the publi...