[RJA-1631][fix] Frontend returned 503, but UI doesn't say anything, it's just hanged
[RJA-1583]UI: Error message should be more informative
[RJA-1631][fix] handling 500 http error code on UI
Merge pull request #774 from bugzmanov/fb-remoting

Major bugs
[RJA-1631][fix] handling 500 http error code on UI
Merge pull request #776 from bugzmanov/fb-remoting

[RJA-1631][fix] handling 500 http error code on UI
[RJA-xxx][fix] micro optimization
[RJA-1469] [feature] - self link in list projects, wrapper, JSON
serializer
Merge pull request #773 from rsvato/agents

[RJA-1598] [feature] - self link in list projects
[RJA-1469] [feature] - tests api fixed for changed rest structure
Merge pull request #780 from rsvato/agents

[RJA-1469] [feature] - tests api fixed for changed rest structure
[RJA-1568][fix] 503 Error reading remote answer when user is added more than 399 groups
Merge pull request #777 from bugzmanov/fb-remoting

[RJA-xxx][fix] micro optimization
[RJA-1531][fix] Roles: null is displayed instead of last name when is it doesn't exist
[RJA-1589][fix] REST: Roles: Nonexistent user and group were added to project roles (ldap was configured)
  - disabled user/groups validation in system settings;
  - added responses about nonexistent users to REST methods;
  - updated services;
  - made refactoring;