Added new users to the monetdb.
requested to merge dev/MIP-750/create-two-roles-that-limits-the-access-modification-of-the-primary-data-table into master
Created by: KFilippopolitis
- Now the master user is renamed to 'admin'.
- Added 2 new users 'executor' and 'guest'.
- User 'executor' can only retrieve data from schemas created by mipdb.
- New mipdb version 2.0.1
- MIP-Engine will execute queries to the database as 'executor'.
- Passwords for the users 'executor', 'admin' are now dynamic, and they are provided as environmental variables.