refactor(Link/_voteForLink): Use Array#some

Instead of using Array#map, to build a list of IDs of users who voted,
and then use Array#includes to check if the user already voted, we can
use Array#some.
The main advantage is that when iterating, as soon as the callback returns
`true` the iteration stops.
See:
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/some

Signed-off-by: Adrian Oprea <adrian@oprea.rocks>

Author: oprearocks

src/components/Link.js

@@ -21,11 +21,11 @@ class Link extends Component {
       </div>
     )
   }
-
+  
   _voteForLink = async () => {
     const userId = localStorage.getItem(GC_USER_ID)
-    const voterIds = this.props.link.votes.map(vote => vote.user.id)
-    if (voterIds.includes(userId)) {
+    const userHasAlreadyVoted = this.props.link.votes.some(vote => vote.user.id === userId)
+    if (userHasAlreadyVoted) {
       console.log(`User (${userId}) already voted for this link.`)
       return
     }