OAKLAND — Attendance appeared to be close to normal when Oakland schools reopened this morning as Douglas County health officials worked to confirm whether an illness that sickened about a 100 students last week was the highly contagious norovirus. Oakland schools reopened after closing Wednesday afternoon when about a fifth of the student population got sick with symptoms that included vomiting and diarrhea. Superintendent Nanette Hagen said an assembly held this morning to celebrate the high school football team winning a state championship Saturday was well attended. “Our stands were pretty close to full,” she said. “They looked pretty close …