Split posts on newline

Slack lets you write posts with multiple paragraphs.  We were joining
everything together, but I think preserving the original newlines will
make things more readable.

Signed-off-by: Anna Schumaker <Anna@NoWheyCreamery.com>

slack/chat.py

@@ -47,7 +47,7 @@ class Message:
         self.__ts   = json["ts"]
         self.__time = datetime.fromtimestamp(float(self.__ts))
         self.__user = users.info(json.get("user", None))
-        self.__text = [ json["text"].encode("utf-8").decode(errors="replace")]
+        self.__text = json["text"].encode("utf-8").decode(errors="replace").split("\n")
 
     def __lt__(self, other):
         return self.__time < other.__time