Renamed HalItem -> HalResource

- Refactored all terminology mentioning "item" to use the term
  "resource" instead.
Updated docs

- s/HalItem/HalResource/g
Update docs

- Use "resource" terminology instead of "item"
- s/ResourceHttpOptions/CollectionHttpOptions/ and
  s/ItemHttpOptions/ResourceHttpOptions/
Merge branch 'feature/item-resource-rename' into develop

Refactored terminology to replace "item" with "resource"