automated data cleaning: row level students_by_school sanity checks

[almartin82]

from the KIPP data retreat, here are some things we should do some sanity checks on when mv object is created from the

• dob is reasonable for a K-12 student
• dob is reasonable for the student's grade level peers
• grade level progression is reasonable for a student

[almartin82]

@chrishaid add more comments as things occur to you here