Feature/lint staged

[nicholasio]

Original PR: #23,

This PR ensures that all code is passing our lint process prior to commit. We can also run phpcs to ensure our PHP code is passing as well, but I haven added phpcs as we still need to work on our phpcs rules.
When commiting, if a JS code fails to pass the lint, commit will be aborted and issues will have to be fixed. This helps (and forces) engineers to stick to our standards and by doing this we can catch a lot of common issue/mistakes even before the code gets pushed.
If this looks good and is approved for merge I'll do the same for the plugin repo.

[timwright12]

@nicholasio Works great for me, please add to plugin repo. It's probably a low probability that JS linting errors will be pushed to a repo since we have to run build and an engineer is also probably running a watch command while work, but good to have an extra line of defense.

I think it's more likely that PHP issues would get committed, so it's be awesome if we would add that linting in at some point as well!

[nicholasio]

@timwright12 yeah, I do have something like this for PHP but it's using VIP Go rules since we don't have our own PHPCS rules yet. I know @tlovett1 mentioned we're working on PHPCS, but not sure where is it at.

[timwright12]

@nicholasio Gotcha, thanks! I"ll ping TL offline about it.