GUI: fixed refresh of user name on tab when changed (perun admin - user detail)
Add working with null givenName (firstName) of User to LDAPc

- in main,java when incializing users
- in updateUser when firstName is null
- in createUser when firstName is null
Merge pull request #279 from stavamichal/Ldap-NullInFirstNameOfUser

Add working with null givenName (firstName) of User to LDAPc
Merge pull request #280 from zlamalp/fixup2

GUI: fixed refresh of user name on tab when changed (perun admin - user detail)