Merge pull request #226 from adamarla/master

Update time stamp on refresh
Added method to return the (likely) sektion for which the exam was made ...
Remove any redundant whitespace in sektion's name before titleizing
Send weekly & monthly synopsis only to teachers

Previously, when submissions for all students came together,
it made sense to send a mail when the last attempt was graded.

Now, because of mobile uploads, scans can come in anytime.
Hence, its best to give a weekly and monthly synopsis only.
Merge branch 'gredits'
Report mean in teacher digest as average / total
Merge branch 'gredits'
Center align text in table rows
Merge branch 'gredits'
Send a nightly mail to teachers about scans received ...

No need to trigger a mails everytime one scan comes in ( as now happens
with mobile uploads )
Merge branch 'gredits'
[upload_summary] -> Minor edits ...

Students after the first one in a sektion share the same quiz and exam.sektion
as the first student.

However, if the exam/sektion changes, then we should list the new exam
along with the first student that then comes up
Merge branch 'gredits'
Corrected logical bug in send_upload_summary
Corrected logical bug in Teacher::send_upload_summary
typo with field label (json)
Merge remote-tracking branch 'upstream/master'