fix(core): made sure self links at document level use service-url-provider as base url

[vicmosin]

Resolves #789

[vicmosin]

@remmeier
made my version of #793

1. I saw you comment about wrong place for calculating the proper URL and imo the place you suggested is also isn't perfect. I find HttpRequestContextBaseAdapter to be bound to current HTTP request, therefor it would be confusing to put there ServiceUrlProvider-related URLs. QueryContext, on the other hand, fits perfectly as it holds not only HTTP stuff but crnk context about current query, so I extended it.
2. I could not find a good place for integration test so used spring-boot-example project to have the new test which checks the links without any additional mocking

[remmeier]

thx!

[datagitlies]

is there an ETA for a new release with this fix @remmeier ?