More Tests, Unified Input Parser, Modularization

[ccpandhare]

I have added more tests in this Pull Request.
My work on the Unified Input isn't over so it can't be merged in.

[ccpandhare]

I could complete the Unified Input Parser today itself. So pushed that in too.
It reduces file size and input is parsed in a more central manner.

[ccpandhare]

I have broken down ImageSequencer.js into various Modules as suggested in #26.

I have a small problem here @jywarren. That is of nomenclature. I am really confused as to how to name these new files which have been generated.
For instance,
The function addSteps now lives in src/AddSteps.js
Should the file be called AddSteps.js or Module.AddSteps.js or something else?
What is the convention here?

Also, Added the method loadImages to the Unified Input Parser.

Also, updated the syntax for the loadImages method to allow callbacks for JSON Inputs as well and updated the Readme.md regarding the same.

[jywarren]

It's a matter of style. In https://github.com/publiclab/PublicLab.Editor, I tended towards longer names, but you can also use directories to group and organize, so for example:

/src/modules/addSteps.js

I think that's nice and succinct, and as long as you respect the same convention everywhere, that's fine.

Is this ready? I'd like, as soon as possible, to be working in smaller, self-contained PRs so that it's easier for me (and others) to evaluate the one thing each PR intends to do, look at its implementation and the test which demonstrates that function, and merge it in. I know you're in a "bootstrapping phase" right now so this is OK, but the sooner we merge this in and start working in smaller pieces, the better. Is this ready to merge?

[jywarren]

If it's ready to go, please merge it in! And we can start on the next round of changes.

[ccpandhare]

Okay!