Implement Database best-practises

[dmohns]

Reason: Currently, in the Postgres DB that is used for the backend some best practices are not implemented. For example

• Make column names intuitive. There is a column called ExternalID However, this column is the internal non-user facing id of devices. The actual “external” ID, that is set by the device operator is called developerExternalId
• Make column names consistent. Postgres is case-sensitive. Sometimes we have externalId sometimes device_externalid
• roleId in user table should be a FOREIGN KEY to user_role

Steps: Implement best practices from the list above.

Definition of done: Implement best practices from the list above.