Show an avatar with initials

### Default

```
<Avatar />
```

### with initials only
#### with name

```
<Avatar text="CD" />
```

### with image instead of initials

```
<Avatar image="https://cozy.io/fr/images/cozy-logo_white.png" />
```

### Available sizes: small, medium (default)
```
<div>
  <div>
    <Avatar size="small" />
    <Avatar text="CD" size="small" />
    <Avatar image="https://cozy.io/fr/images/cozy-logo_white.png" size="small" />
  </div>
  <div>
    <Avatar size="medium" />
    <Avatar text="CD" size="medium" />
    <Avatar image="https://cozy.io/fr/images/cozy-logo_white.png" size="medium" />
  </div>
</div>
```
