REGISTRAR: allow to check for similar users when no appId is known
RPC: support for checking similar users based on latest application
GUI: check for similar users by latest application

- also return rich users to display better data
- updated messages
REGISTRAR: fixed SQL in check for similar users
GUI: better display of results when checking for similar users
REGISTRAR: better sorting of applications to show latest first
GUI: better sorting of applications to show latest first
Merge pull request #429 from zlamalp/similar

REGISTRAR,GUI: improved UX when searching for similar users