message: clean up Avatar
diff: -import React, {Component} from 'react'
  +import React from 'react'
  import classnames from 'classnames'
  -export default function Avatar(props) {
  +const Avatar = props => {
  const {
  username,
  size = 20,
  baseURL = 'https://avatars.githubusercontent.com/',
  alt,
  - params,
  + child,
  ...rest
  } = props
  - const query = new URLSearchParams(params)
  - query.set('v', 3) // is this necessary?
  - query.set('s', size)
  - const src = `${baseURL}${username || 'github'}?${params}`
  + const query = new URLSearchParams({
  + v: 3, // XXX is this necessary?
  + s: size * 2
  + })
  return (
  - <img {...props} src={src} width={size} height={size} alt={alt || username}/>
  + <img
  + className={classnames(
  + 'avatar',
  + {
  + 'avatar-small': size <= 48,
  + 'avatar-child': child,
  + }
  + )}
  + src={`${baseURL}${username || 'github'}?${query}`}
  + width={size}
  + height={size}
  + alt={alt || username}
  + />
  )
  }
  +
  +export default Avatar
  