Merge master to feature/stabilization
FORUM-588 | [Cluster] Issues with displaying in Forum
FORUM-725 | [Ispn][cluster]Topic isn't displayed in Node1.
FORUM-742 | [Poll] NumberFormatException when click on vote without selecting an answer
FORUM-606 | [Forum] Slow first loading of Users
UI-3312: UI Bug in answer after change to  language
FORUM-606 | Fix problem of NullPointerException when start server
Merge feature/stabilization to master