205 update the webapp to use the new db

[danielgron]

Changed to use postgres instead of sqlite. Long term we will want to use gorm as well here, but since ui tests will be running soon we need a working implementation asap.

Tests are passing, and I've done a manual test with the live db to see that the handling of ssl mode works as intended.

[Romes8]

If the comment above is resolved its good.

My testing:

• [x] Started docker images
• [x] Ran simulator script
• [x] Check the UI as messages appear as simulator creates tweets.
• [x] Works as intended