UFAL/Health report bugs and improvements

[milanmajchrak]

The original issue:
ufal#1328

Another idea: Add a health report check in the end of the email/report which does not have any diff info.

[Paurikova2]

@milanmajchrak In that PR there are only improvements from Milan Kuchtiak. We should think about what else from that issue we want and create a new issue and PR.