Move all the raw tweets for tests into their own JSON files

Seems better to have the raw data as JSON, like it comes from the API,
then load it into python objects for each test.

tests/tweets/identical_urls.json

@@ -0,0 +1,34 @@
+{
+  "entities":{
+    "hashtags":[
+
+    ],
+    "user_mentions":[
+
+    ],
+    "symbols":[
+
+    ],
+    "urls":[
+      {
+        "display_url":"buff.ly/2sEhrgO",
+        "expanded_url":"http://buff.ly/2sEhrgO",
+        "indices":[
+          42,
+          65
+        ],
+        "url":"https://t.co/W0uArTMk9N"
+      },
+      {
+        "display_url":"buff.ly/2sEhrgO",
+        "expanded_url":"http://buff.ly/2sEhrgO",
+        "indices":[
+          101,
+          124
+        ],
+        "url":"https://t.co/W0uArTMk9N"
+      }
+    ]
+  },
+  "full_text":"Use Cases, Trials and Making 5G a Reality https://t.co/W0uArTMk9N #5G #innovation via @5GWorldSeries https://t.co/W0uArTMk9N"
+}