Update src/sentry/constants.py

support for oracle
Update src/sentry/utils/dates.py

DATE is a keyword in oracle.
So it should be TRUNC("DATE") instead of TRUNC(date)
Update src/sentry/web/frontend/groups.py
Update src/sentry/web/frontend/groups.py
Update src/sentry/utils/dates.py
Merge branch 'master' of git://github.com/askfor/sentry into askfor-master
Tidying up