Add ability for an administrator to remove any video (#61)

* Add ability for an admin to remove every video on the pod.

* Server: add BlacklistedVideos relation.

* Server: Insert in BlacklistedVideos relation upon deletion of a video.

* Server: Modify BlacklistedVideos schema to add Pod id information.

* Server: Moving insertion of a blacklisted video from the `afterDestroy` hook into the process of deletion of a video.

To avoid inserting a video when it is removed on its origin pod.
When a video is removed on its origin pod, the `afterDestroy` hook is fire, but no request is made on the delete('/:videoId') interface.
Hence, we insert into `BlacklistedVideos` only on request on delete('/:videoId') (if requirements for insertion are met).

* Server: Add removeVideoFromBlacklist hook on deletion of a video.

We are going to proceed in another way :).
We will add a new route : /:videoId/blacklist to blacklist a video.
We do not blacklist a video upon its deletion now (to distinguish a video blacklist from a regular video delete)
When we blacklist a video, the video remains in the DB, so we don't have any concern about its update. It just doesn't appear in the video list.
When we remove a video, we then have to remove it from the blacklist too.
We could also remove a video from the blacklist to 'unremove' it and make it appear again in the video list (will be another feature).

* Server: Add handler for new route post(/:videoId/blacklist)

* Client: Add isBlacklistable method

* Client: Update isRemovableBy method.

* Client: Move 'Delete video' feature from the video-list to the video-watch module.

* Server: Exclude blacklisted videos from the video list

* Server: Use findAll() in BlacklistedVideos.list() method

* Server: Fix addVideoToBlacklist function.

* Client: Add blacklist feature.

* Server: Use JavaScript Standard Style.

* Server: In checkUserCanDeleteVideo, move the callback call inside the db callback function

* Server: Modify BlacklistVideo relation

* Server: Modifiy Videos methods.

* Server: Add checkVideoIsBlacklistable method

* Server: Rewrite addVideoToBlacklist method

* Server: Fix checkVideoIsBlacklistable method

* Server: Add return to addVideoToBlacklist method

server/controllers/api/videos.js

@@ -93,11 +93,13 @@ router.get('/:id',
   validatorsVideos.videosGet,
   getVideo
 )
+
 router.delete('/:id',
   oAuth.authenticate,
   validatorsVideos.videosRemove,
   removeVideo
 )
+
 router.get('/search/:value',
   validatorsVideos.videosSearch,
   validatorsPagination.pagination,
@@ -108,6 +110,13 @@ router.get('/search/:value',
   searchVideos
 )
 
+router.post('/:id/blacklist',
+  oAuth.authenticate,
+  admin.ensureIsAdmin,
+  validatorsVideos.videosBlacklist,
+  addVideoToBlacklist
+)
+
 // ---------------------------------------------------------------------------
 
 module.exports = router
@@ -622,3 +631,19 @@ function reportVideoAbuse (req, res, finalCallback) {
     return finalCallback(null)
   })
 }
+
+function addVideoToBlacklist (req, res, next) {
+  const videoInstance = res.locals.video
+
+  db.BlacklistedVideo.create({
+    videoId: videoInstance.id
+  })
+  .asCallback(function (err) {
+    if (err) {
+      logger.error('Errors when blacklisting video ', { error: err })
+      return next(err)
+    }
+
+    return res.type('json').status(204).end()
+  })
+}