Fix Travis CI issue - The unauthenticated git protocol on port 9418 i…

…s no longer supported.

patch by Ekaterina Dimitrova; reviewed by Brandon Williams for CASSANDRA-17545

.travis.yml

@@ -10,7 +10,7 @@ script:
   # we use flake8 because it allows us to ignore other warnings
   # exclude the thrift directories - they contain auto-generated code
   # - flake8 --ignore=E501,F811,F812,F822,F823,F831,F841,N8,C9 --exclude=thrift_bindings,cassandra-thrift .
-  - git remote add apache git://github.com/apache/cassandra-dtest.git
+  - git remote add apache https://github.com/apache/cassandra-dtest.git
   - git fetch apache # fetch master for the next diff
   # feed changed lines with no context around them to pycodestyle
   # I know we don't enforce line length but if you introduce