Link with a child of integer 0 returns returns the href

If I have something like:
```
<SecureLink href={url}>{0}</SecureLink>
```
It should have a link with 0 as the clickable link. This would be the behavior if I had something like 
```
<a href={url}>{0}</a>
```

Looking at the code it because you check the boolean of the children. However this check should probably be for just null, undefined, and empty string.