Eliminate when.js dependency in distribution

[techfg]

Per @jamietre comment here, to minimize the changes required to support NPM, etc. when.js should be removed and replaced with native promises.

[techfg]

A few notes on approach/benefits of commit:

1. Goal was to minimize changes to existing code base as a priority so given this, left the "defer" pattern and shimed/polyfilled a native promise solution. Would be better to refactor and move away from defer but wanted to minimize any risk. All tests pass before/after.

2. There was an existing bug in the when.js library (imagemapster was using 1.2.0, latest version is 3.7.8) that this line of code was subject to. In short, the when.all when passed an array would not actually check easy promise in the array and instead would immediately resolve treating the array itself as a value. This was later fixed in when.js (around 1.5 I think) but IM suffered from it. The added benefit of the changes in this commit are that this gap is closed and should no longer be an issue.

3. when.js is still used by the testing framework, only removed when.js from src/dist.