Use a better index for hashed_url

It'll most often be used in addition to the `user_id`.
Also, automatically generate the hash when saving the url.
Switch from `md5` to `sha1`.

src/Wallabag/CoreBundle/Command/GenerateUrlHashesCommand.php

@@ -69,7 +69,7 @@ class GenerateUrlHashesCommand extends ContainerAwareCommand
 
         $i = 1;
         foreach ($entries as $entry) {
-            $entry->setHashedUrl(hash('md5', $entry->getUrl()));
+            $entry->setHashedUrl(hash('sha1', $entry->getUrl()));
             $em->persist($entry);
 
             if (0 === ($i % 20)) {

src/Wallabag/CoreBundle/DataFixtures/EntryFixtures.php

@@ -89,7 +89,6 @@ class EntryFixtures extends Fixture implements DependentFixtureInterface
         foreach ($entries as $reference => $item) {
             $entry = new Entry($this->getReference($item['user']));
             $entry->setUrl($item['url']);
-            $entry->setHashedUrl(hash('md5', $item['url']));
             $entry->setReadingTime($item['reading_time']);
             $entry->setDomainName($item['domain']);
             $entry->setMimetype($item['mime']);

src/Wallabag/CoreBundle/Entity/Entry.php

@@ -26,7 +26,7 @@ use Wallabag\UserBundle\Entity\User;
  *     indexes={
  *         @ORM\Index(name="created_at", columns={"created_at"}),
  *         @ORM\Index(name="uid", columns={"uid"}),
- *         @ORM\Index(name="hashed_url", columns={"hashed_url"})
+ *         @ORM\Index(name="hashed_url_user_id", columns={"user_id", "hashed_url"})
  *     }
  * )
  * @ORM\HasLifecycleCallbacks()
@@ -79,7 +79,7 @@ class Entry
     /**
      * @var string
      *
-     * @ORM\Column(name="hashed_url", type="string", length=32, nullable=true)
+     * @ORM\Column(name="hashed_url", type="string", length=40, nullable=true)
      */
     private $hashedUrl;
 
@@ -324,6 +324,7 @@ class Entry
     public function setUrl($url)
     {
         $this->url = $url;
+        $this->hashedUrl = hash('sha1', $url);
 
         return $this;
     }

src/Wallabag/CoreBundle/Helper/ContentProxy.php

@@ -248,8 +248,6 @@ class ContentProxy
     {
         $this->updateOriginUrl($entry, $content['url']);
 
-        $entry->setHashedUrl(hash('md5', $entry->getUrl()));
-
         $this->setEntryDomainName($entry);
 
         if (!empty($content['title'])) {