Post an event

[edwardisintou]

Function for user to post their own events, it needs to fix error of not showing message to user when they post a duplicate event

[lauhart]

Great Start.

A few recommendations:

• [ ] Firstly, project requirement is to use SQLAlchemy instead of create_database.py (see Security branch - think we should merge this to main first)
• [ ] Secondly, would recommend a drop down menu to select the event date/time (it is currently too tedious for the user to add all this manually)