PYTHON-2397: MongoClient(ssl=True, tls=False) fails with an AttributeError (#592)

(cherry picked from commit 85f9f7a)

Author: guanlinzhou

pymongo/mongo_client.py

@@ -655,7 +655,7 @@ def __init__(
         username = None
         password = None
         dbase = None
-        opts = {}
+        opts = common._CaseInsensitiveDictionary()
         fqdn = None
         for entity in host:
             if "://" in entity:

test/test_client.py

@@ -452,6 +452,9 @@ def test_uri_security_options(self):
             MongoClient('mongodb://localhost/?tlsInsecure=true',
                         connect=False, ssl_cert_reqs=True)
 
+        # Conflicting kwargs should raise InvalidURI
+        with self.assertRaises(InvalidURI):
+            MongoClient(ssl=True, tls=False)
 
 class TestClient(IntegrationTest):