Refactor REST item_tags entity a bit.
- change field name "tag_names" --> "names"
- tweak how the entity is put into the response (Rest_ItemTags::get_response())
- revise unit tests to match
- ensure that the names are trimmed before adding the tags
Merge pull request #440 from shadlaws/fixes_20130630

Refactor REST item_tags entity a bit.