Task/581 v1 context entities 4ops

### Description
First four of the new batch of convops:
PUT/POST/GET/DELETE /v1/contextEntities/type/<type>/id/<id>

One bug found and fixed (type was empty in respònses).

Functional tests for JSON and XML.

I guess this is related with "One bug found and fixed (type was empty in respònses)".

Please, add a line in CHANGES_NEXT_RELEASE about this bugfixing (either linked to a github issue or not).