Properly escape data in the request code

It was only escaping the first quote, all other quotes and other characters that require to be escaped (like line breaks) were not being escaped. JSON.stringify is a good function to handle this.

Update README.md

Added Skitzen.com as a API host

Add trans.zillyhuhn.com

Reduce Docker image size

Expose api_keys in frontend settings

decrease counter if the user wait after the slowdown notice

Upgrade to Argos Translate 1.5.3

This is useful for applications that want to know beforehand if usage of
an API key is supported.

Require API key for submitting suggestions

Also removes limiter exemption

Expose require_api_key_origin in frontend settings

This is useful for applications that want to know beforehand if an API
key is necessary before accessing the running instance.

Upgrade to argos-translate-files v1.0.4

[WIP] Add files translation