Handle Exif orientations for JPEG images (fixes #1670)

[prewett-toptal]

Implements simple Exif parsing for JPEG files, enough to determine if there is an Exif tag, and if that tag has an orientation, rotates the image. This makes node-canvas compatible with browsers, which also rotate the image based on the Exif orientation tag. This fixes #1670.

A simple test program for 2 of the 3 paths follows. This loads the JPEG, draws it to the canvas, and saves the result to ./test.png. Test images are available (among other places) from https://github.com/noell/jpg-exif-test-images:

`
const fs = require('fs')
const { createCanvas, loadImage } = require('canvas')

// One source of sample images with EXIF rotations is at
// https://github.com/noell/jpg-exif-test-images

const imagePath = process.argv[2];
loadImage(imagePath).then(image => {
const w = image.naturalWidth
const h = image.naturalHeight
const canvas = createCanvas(w, h/, 'PDF'/) // uncomment to test the mime device path
const context = canvas.getContext('2d')
context.fillStyle = '#f0f';
context.fillRect(0, 0, w, h);
context.drawImage(image, 0, 0, w, h)

const buffer = canvas.toBuffer('image/png')
fs.writeFileSync('./test.png', buffer)

}).catch(e => {
console.log("[error]", e);
})
`

Since one major use of node-canvas is in the fabric project, which has not updated to the newly release 3.0 version yet, I think it would be helpful to backport to 2.11 (they use 2.11.2 at the moment), since it seems that 3.0 makes breaking changes for fabric. I initially made these changes on a branch from the v2.11.2 tag, and they merged with no problems, so I expect this changeset can be merged into a 2.11 branch. I can also create a separate pull request to whatever branch would be appropriate, if that is helpful.

• Have you updated CHANGELOG.md?

[prewett-toptal]

Would it be possible to get a yes/no on this? Thanks!