feat(apigen): Add apigen and get working on all dev environments

[lalitaCF]

It was broken on Windows, so we removed it for now. ^^

"docs": "apigen generate ./src --destination ./docs",

[cyberhck]

Don't remove it, make it work instead, or leave it working on Linux, most probably we'll not do it on development machine, but instead automatically commit via travis

[cyberhck]

Idea is to automatically commit stuff when something gets merged to master and target branch is gh-pages, don't care if it works on windows, I don't want devs to waste time solving merge conflicts

[dacgray]

It will be confusing and it the boilerplate would be broken if we include a script that doesn't work on the majority of developers' machines.

It's a very nice to have though. so we should get it working,

[cyberhck]

Again, idea is to automatically commit on travis, as of not it's just an experiment before we call it "this is boilerplate we're presenting", so to make things easier, apigen will be in (at least for now)

no devs will be running this by hand, actually it won't be in composer.json at all

say it's in for now, just because it's buggy, doesn't mean we remove a feature, we instead file a bug report, as we'd do with any other package.

And getting it working on windows would be a "nice touch", but again, no body should care, because I can't stress this enough, developer won't even know that this is being used unless they go through .travis.yml

Only time you'd fiddle around with this package would be when you're doing something related, which won't be commited (we'll be using composer merge plugin to test that out), as of now to test the pipeline (merge to master -> commit and push to github pages), we're including in composer.json because boilerplate isn't ready yet.