Issue #284 Handle ssl connections

* `RedisPublisher` handles `ssl` flag
* Update docs

docs/installation.rst

@@ -82,6 +82,15 @@ override these values
 
 .. note:: Specify only the values, which deviate from the default.
 
+If your Redis instance requires a SSL connection, set the ``ssl`` flag to ``True``: 
+
+.. code-block:: python
+
+	WS4REDIS_CONNECTION = {
+	    ...
+	    'ssl': True
+	}
+
 If your Redis instance is accessed via a Unix Domain Socket, you can configure that as well:
 
 .. code-block:: python

ws4redis/publisher.py

@@ -3,7 +3,11 @@
 from ws4redis import settings
 from ws4redis.redis_store import RedisStore
 from ws4redis._compat import is_authenticated
-from redis.connection import UnixDomainSocketConnection
+from redis.connection import (
+    UnixDomainSocketConnection,
+    Connection,
+    SSLConnection,
+)
 
 if 'unix_socket_path' in settings.WS4REDIS_CONNECTION:
     # rename 'unix_socket_path' to 'path' and pass as args
@@ -12,7 +16,15 @@
     del conn_args['unix_socket_path']
     redis_connection_pool = ConnectionPool(connection_class=UnixDomainSocketConnection, **conn_args)
 else:
-    redis_connection_pool = ConnectionPool(**settings.WS4REDIS_CONNECTION)
+    conn_args = dict(settings.WS4REDIS_CONNECTION)
+    if conn_args.pop("ssl", None):
+        connection_class = SSLConnection
+    else:
+        connection_class = Connection
+    redis_connection_pool = ConnectionPool(
+        connection_class=connection_class, **conn_args
+    )
+
 
 class RedisPublisher(RedisStore):
     def __init__(self, **kwargs):