Add gzip compression, can be enabled/disabled in config.js

[shindakun]

Closes #1305

• added compression module
• added new server config variable: gzip
• gzip enabled by default in production disabled in other environments

[halfdan]

@shindakun The PR is much appreciated - but can we first have a discussion on those topics?

[shindakun]

@halfdan certainly, I had already done have the work so I figured I'd make it pretty and submit.

[shindakun]

@halfdan Yeah I just noticed npm install compression -save seems to have changed the CRLF.

[shindakun]

compress may be a better variable name, since it gets the point across clearly. And your right I didn't need to sprinkle the gzip: false around, since it will be inherently false (falsy?). I'll leave the PR as it is right now, pending further discussions on the matter.

[ErisDS]

@shindakun Thanks for taking the time to PR this 👍

[shindakun]

@ErisDS I'll update my PR this evening after work.

[twigs67]

@shindakun gzip is not being applied to image/jpeg and image/png content types. Before I add it to nginx, is there a reason this was left out? Most other file types are encoding via gzip.

[shindakun]

@twigs67 heh that was a while ago but if I recall correctly I simply decided to rely on the default filter. It will use a secondary module https://www.npmjs.com/package/compressible which in turn by default only says "textbased" MIME types are compressible.

But, if I was to be faced with this now on my own site... I'd do what you are looking into and let Nginx take care of all the heavy lifting. Though I do think it's redundant to compress png and jpeg since in many cases they are likely already compressed and text is far more likely to "need" compressing.

Smaller transfer sizes are a good thing for everyone though.