NCT-45: Improve Loopy API Client with true objects instead of NSDictionary for JSON-based API calls

@imosquera This commit is branched off of feature/device-settings as it depended on changes made there (also up for review in a separate pull request); this pull request includes two stories that are similarly related:

LIOS-43: Update JSON object tests with deep-validation checking
LIOS-54: Improve Loopy API Client with true objects instead of NSDictionary for JSON-based API calls

It's a biggie! But yes, doing full-on objects, while a bit more verbose and requiring a bit of conversion effort to "JSON-ify", definitely adds to maintainability and readability.