Merge pull request #5 from vojtechhlavka/master

hodne zmen v testech a implementaci
a
added test crate/updateWithExitingId/Number a vym

azani bilych mezer
a
mensi upravy u GuestManagerImp
PRIDANI VYTVORENI A SMAZANI TABULEK
temer implmenentovan backend
Opraveny chyby v testech a mezery v SQL dotazu