Bug fixes for 1.3

Status: **Opened for mergey-merge**

Reviewers: **@rrjamie or @jansepar**
Linked PRs: **https://github.com/mobify/mobifyjs/pull/264**

## Changes
- Fixes API shims to have proper 1.1-style behaviour

## How to test-drive this PR
- preview a project that uses the jazzcat and image resizer apis, ensure things appear to be working