RTGOV-610 Convert from Errai RPC to standard JAX-RS services. Meant that current situation notification mechanism had to be enabled, but will be re-implemented as part of RTGOV-611

Situations mostly working - known issues are context not displayed, message content not displayed (even though both are returned), assign causes update to situation, but not reflected in updated buttons, and the situation is not immediately updated
Merge pull request #227 from objectiser/RTGOV-610

RTGOV-610 Convert from Errai RPC to standard JAX-RS services. Meant that...