ConsoleReporter: do not color if !isTTY

[jrr]

Summary

Given the general problem of yarn emitting console color codes at inappropriate times, this PR tackles one particular case that's been annoying me.

Before:

jrr@jrrmbp ~> yarn versions |more
yarn versions v1.9.4
{ yarn: ESC[32m'1.9.4'ESC[39m,
  http_parser: ESC[32m'2.8.0'ESC[39m,
  node: ESC[32m'8.11.3'ESC[39m,
  v8: ESC[32m'6.2.414.54'ESC[39m,
  uv: ESC[32m'1.19.1'ESC[39m,
  zlib: ESC[32m'1.2.11'ESC[39m,
  ares: ESC[32m'1.10.1-DEV'ESC[39m,
  modules: ESC[32m'57'ESC[39m,
  nghttp2: ESC[32m'1.32.0'ESC[39m,
  napi: ESC[32m'3'ESC[39m,
  openssl: ESC[32m'1.0.2o'ESC[39m,
  icu: ESC[32m'60.1'ESC[39m,
  unicode: ESC[32m'10.0'ESC[39m,
  cldr: ESC[32m'32.0'ESC[39m,
  tz: ESC[32m'2017c'ESC[39m }
Done in 0.02s.

After:

jrr@jrrmbp ~/r/yarn (fix/console-reporter-colors)> ./bin/yarn versions |more
yarn versions v1.10.0-0
{ yarn: '1.10.0-0',
  http_parser: '2.8.0',
  node: '8.11.3',
  v8: '6.2.414.54',
  uv: '1.19.1',
  zlib: '1.2.11',
  ares: '1.10.1-DEV',
  modules: '57',
  nghttp2: '1.32.0',
  napi: '3',
  openssl: '1.0.2o',
  icu: '60.1',
  unicode: '10.0',
  cldr: '32.0',
  tz: '2017c' }
Done in 0.13s.

See issue here: #728

---

This band-aids one particular symptom that has been annoying me in my CI output, but perhaps in the future a larger refactor could:

• reduce the number of special cases (there's a surprising number of isTTY checks in a few different files)
• rely on Chalk's built-in terminal detection. (shouldn't we get this for free? "Color support is automatically detected", https://github.com/chalk/chalk#chalklevel)

[arcanis]

While I understand the rational behind this change, I'd prefer if you could simply disable the colors before they are added. Triming them is a tad more generic, but seems like a hack to me:

yarn/src/reporters/console/console-reporter.js

Lines 123 to 128 in 926285a

	value = inspect(value, {
	breakLength: 0,
	colors: true,
	depth: null,
	maxArrayLength: null,
	});

[arcanis]

Please disable the colors rather than post-process the messages.

[jrr]

@arcanis thanks for the feedback, and for pointing me toward the inspect() call. This is my first time inside yarn and I'm pretty lost.

Agree that it's better to not even emit colors in the first place, rather than strip them out afterward. And that brings the diff down to one line!

[arcanis]

Looks good, thanks!