Add support to linkify links and mentions on twitter

This converts links in tweets to a tags. We also convert the displayed
text to the target of the twitter short URL. Mentions are linked to the
users twitter page.

(imported from commit 192d5546a7eea82759f9ae30d82c102aed15ff71)

zerver/lib/bugdown/testing_mocks.py

@@ -2,10 +2,8 @@ from __future__ import absolute_import
 
 import ujson
 
-def twitter(tweet_id):
-    if tweet_id not in ["112652479837110273", "287977969287315456", "287977969287315457"]:
-        return None
-    return ujson.loads("""{
+
+NORMAL_TWEET = """{
   "coordinates": null,
   "created_at": "Sat Sep 10 22:23:38 +0000 2011",
   "truncated": false,
@@ -62,5 +60,109 @@ def twitter(tweet_id):
     "show_all_inline_media": false
   },
   "in_reply_to_screen_name": "twitter",
-  "in_reply_to_status_id": null
-}""")
+  "in_reply_to_status_id": null,
+  "user_mentions": [
+    {
+      "screen_name": "twitter",
+      "name": "Twitter",
+      "id": 1
+    },
+    {
+      "screen_name": "seepicturely",
+      "name": "Seepicturely",
+      "id": 2
+    },
+    {
+      "screen_name": "boscomonkey",
+      "name": "Bosco So",
+      "id": 3
+    },
+    {
+      "screen_name": "episod",
+      "name": "Taylor Singletary",
+      "id": 4
+    }
+   ],
+  "urls": {
+    "http://t.co/6J2EgYM": "http://instagram.com/p/MuW67/"
+  }
+}"""
+
+MENTION_IN_LINK_TWEET = """{
+  "coordinates": null,
+  "created_at": "Sat Sep 10 22:23:38 +0000 2011",
+  "truncated": false,
+  "favorited": false,
+  "id_str": "112652479837110273",
+  "in_reply_to_user_id_str": "783214",
+  "text": "http://t.co/@foo",
+  "contributors": null,
+  "id": 112652479837110273,
+  "retweet_count": 0,
+  "in_reply_to_status_id_str": null,
+  "geo": null,
+  "retweeted": false,
+  "possibly_sensitive": false,
+  "in_reply_to_user_id": 783214,
+  "user": {
+    "profile_sidebar_border_color": "eeeeee",
+    "profile_background_tile": true,
+    "profile_sidebar_fill_color": "efefef",
+    "name": "Eoin McMillan ",
+    "profile_image_url": "http://a1.twimg.com/profile_images/1380912173/Screen_shot_2011-06-03_at_7.35.36_PM_normal.png",
+    "created_at": "Mon May 16 20:07:59 +0000 2011",
+    "location": "Twitter",
+    "profile_link_color": "009999",
+    "follow_request_sent": null,
+    "is_translator": false,
+    "id_str": "299862462",
+    "favourites_count": 0,
+    "default_profile": false,
+    "url": "http://www.eoin.me",
+    "contributors_enabled": false,
+    "id": 299862462,
+    "utc_offset": null,
+    "profile_image_url_https": "https://si0.twimg.com/profile_images/1380912173/Screen_shot_2011-06-03_at_7.35.36_PM_normal.png",
+    "profile_use_background_image": true,
+    "listed_count": 0,
+    "followers_count": 9,
+    "lang": "en",
+    "profile_text_color": "333333",
+    "protected": false,
+    "profile_background_image_url_https": "https://si0.twimg.com/images/themes/theme14/bg.gif",
+    "description": "Eoin's photography account. See @mceoin for tweets.",
+    "geo_enabled": false,
+    "verified": false,
+    "profile_background_color": "131516",
+    "time_zone": null,
+    "notifications": null,
+    "statuses_count": 255,
+    "friends_count": 0,
+    "default_profile_image": false,
+    "profile_background_image_url": "http://a1.twimg.com/images/themes/theme14/bg.gif",
+    "screen_name": "imeoin",
+    "following": null,
+    "show_all_inline_media": false
+  },
+  "in_reply_to_screen_name": "twitter",
+  "in_reply_to_status_id": null,
+  "user_mentions": [
+    {
+      "screen_name": "foo",
+      "name": "Foo",
+      "id": 1
+    }
+   ],
+  "urls": {
+    "http://t.co/@foo": "http://foo.com"
+  }
+}"""
+
+
+def twitter(tweet_id):
+    if tweet_id in ["112652479837110273", "287977969287315456", "287977969287315457"]:
+        return ujson.loads(NORMAL_TWEET)
+    elif tweet_id == "287977969287315458":
+        return ujson.loads(MENTION_IN_LINK_TWEET)
+    else:
+        return None