A Morris County man employed by a special education school in Somerset County has been arrested on charges he uploaded child pornography to an online app, authorities announced Friday. Richard Kattermann, 31, of Jefferson, was charged with one third-degree count of endangering the welfare of a child through the possession of child sex abuse material, the Morris County Prosecutor’s Office said. He was employed at Montgomery Academy, a school in Basking Ridge that serves students ages 5 to 21, prosecutors said. The Somerset County school offers therapeutic services and highly individualized inst…