Support CORS request filtering

[otsakir]

Currently no CORS related headers are returned in REST API responses preventing use of the API from UI clients on a different domain (RVD-ui).

Exceptions to CORS restrictions can be applied using a filter.

• Add CORS header in responses. Maybe through a ContainerResponseFilter.
• The 'Access-Control-Allow-Origin = *' can be returned as a first iteration

More fine grained control on which origins will be accepted will be added in a separate issue.