Use NODE_ENV (or fall back to 'production' if not set) when running build

[chrisdwheatley]

As suggested by @yoshuawuyts in choojs/create-choo-electron#1 this PR sets NODE_ENV to 'production' by default when running bankai build.

If desired a user can set their own NODE_ENV which will override the default.

I tested this in create-choo-app by running npm run dev and being able to see choo-log output in the console. I then ran npm run buildand served the built files statically and saw no more logs from choo-log in the console (due to the NODE_ENV === 'production' check in create-choo-app).

I also ran NODE_ENV="chugga-chugga-choo-choo" npm run build which meant the 'production' default was overridden and this resulted in choo-log being used as expected.

Tests seem to be failing in CI so I don't think I've regressed anything but happy to take a look at that if I have (or take a look separately).

[Flet]

I think this is great! Does it make sense to add a small note to the README about this? It could lead to surprising behavior for folks who rely on NODE_ENV in their apps, so leaving a breadcrumb would be prudent :)

[chrisdwheatley]

Thanks for the feedback. I'm personally not sure the readme would be the best place for this information, perhaps a better place would be within the cli output when running bankai build, similar to;

bankai/lib/cmd-build.js

Line 32 in 634ea38

log.info('Compiling & compressing files\n')

But along the lines of Running in ${process.env.NODE_ENV} mode\n, or something similar. What do you think?