Add pagination info to get results whatever the HATEOAS status

This is breaking the backward compatibility of collection responses when
HATEOAS is disabled. Collection responses now get always the same response
format. HATEOAS status does only affect the presence of not of the _link
section.

Fixes #355
Fix some failing tests

Sorry about that
Move pagination information fields into a `meta` object
Merge branch 'develop' of https://github.com/nicolaiarocci/eve into pagination-info
flake8 fixes
Docs update for _meta keyword
Changelog update for #364
Merge branch 'rs-pagination-info' into develop