convert existing examples to ethers.js

[metamask]

convert existing examples to ethers.js

[jennypollack]

for encrypt/decrypt

const encrypted = sigUtil.encrypt(key, { data: 'Hello world!' }, 'x25519-xsalsa20-poly1305')
const stringified = JSON.stringify(encrypted)
const buffer = Buffer.from(stringified)
const ethersHex = ethers.utils.hexlify(buffer)
console.log(ethersHex)
const web3Hex = web3.utils.toHex(stringified)
console.log(web3Hex)
console.log(ethersHex === web3Hex) // true

[V1e2n3k4a5t6e7s8w9a10r11l12u13]

Ok