Refactored for removal of Promise shim from dojo/shim, shim issue #21

[rorticus]

This is part of shim #21! We removed the promise shim and are returning the native promise object.

It looks like in Typescript, if you cannot extend Promise and compile down to ES5. So in the mean time, I've created a Promise wrapper thingy, similar to what was in shim. The wrapper includes a finally because Task needed it.

It turns out that the promise shim from dojo/shim was swallowing uncaught errors. When you run the tests now, you get a ton of uncaught error messages (but the tests pass).

Did I mention this is dependent on https://github.com/dojo/shim/pull/41 ?

[codecov-io]

Current coverage is 97.37% (diff: 100%)

Merging #219 into master will decrease coverage by 0.04%

@@             master       #219   diff @@
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  Files            44         45     +1   
  Lines          2326       2359    +33   
  Methods          26         25     -1   
  Messages          0          0          
  Branches        445        449     +4   
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+ Hits           2266       2297    +31   
- Misses           56         58     +2   
  Partials          4          4          

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[kitsonk]

We should rebase this off of master while we are getting dojo/shim#41 sorted out as there has been quite a bit of machinations in there with the integration of dojo-interfaces.

[kitsonk]

Actually this is now independent of dojo/shim#41, because it has now abstracted itself from that, which is good. While there is a risk that when dojo/shim#41 gets published, it causes a regression, but both @rorticus and myself have tested against linked versions of this. This is a great example of decoupling!