- gui now works even without SMTP configured (cert-access URL is printed to the page instead of being sent to the user)
- several fixes in other error handling

simple JS code added to show/hide rows with accounts marked as internal

There's no reason to make them different and this way it simplifies things (for example EasyRSA names certificate files by CN, but we usually identify user by its username).

Most of the functions needed to generate certificates and access them using unique tokens are implemented. Integration with the rest of the system, as well as sending emails, is still missing.

(forgot to add them to repository before)

NiFi connector is now complete

API is authenticated via token requested from Keycloak by simulating normal user login.
A special user account "soctools-user-mgmt" is used to manage user in NiFi (this must be pre-created duing soctools installation).
Many other related changes.

- "Add user" moved to separate page
- Added a UserAccount class as our own representation of user account information

The UI should run from a directory directly under soctools root (or the "SOCTOOLS_BASE" must be modified)

+ added requirements.txt