Reworked inf general announcements
- Changed document format to match the newcome wiki page
- Changed db path from inf.announcements to inf.announce
data.py: Added inf.announce basic json format
util.py: Bugfix parse_greek_dates
- Some months were not properly written, so strptime threw exception
server.py: Changed the restful api
- Inf general announcements moved from /inf/announcements to /inf/announce/genannounce