Just an express server to get personalized recommendations with different managers

to use it:
```yarn```
```yarn dev```

this will start the server on port 3000

then hit the route 
localhost:3000/relational, 
localhost:3000/non-rational,
localhost:3000/local 

to get recommendations using the relational or the non-relational or local adapter. There is also a local adapter working as a demo for the dynamoDB one. 

the rational adapter is using a postgresql database. 
the non-rational adapter is using a dynamodb database.