Optimize the link address

Use https instead of http to ensure the safety without containing our
account/password information

Change-Id: I48ac6c37b0abb4c14e6803f99abb57e275175eba

CONTRIBUTING.rst

@@ -1,13 +1,13 @@
 If you would like to contribute to the development of OpenStack,
 you must follow the steps in this page:
 
-   http://docs.openstack.org/infra/manual/developers.html
+   https://docs.openstack.org/infra/manual/developers.html
 
 Once those steps have been completed, changes to OpenStack
 should be submitted for review via the Gerrit tool, following
 the workflow documented at:
 
-   http://docs.openstack.org/infra/manual/developers.html#development-workflow
+   https://docs.openstack.org/infra/manual/developers.html#development-workflow
 
 Pull requests submitted through GitHub will be ignored.
 

HACKING.rst

@@ -1,4 +1,4 @@
 dragonflow Style Commandments
 ===============================================
 
-Read the OpenStack Style Commandments http://docs.openstack.org/developer/hacking/
+Read the OpenStack Style Commandments https://docs.openstack.org/developer/hacking/

README.rst

@@ -10,10 +10,10 @@ Team and repository tags
 Distributed SDN-based Neutron Implementation
 
 * Free software: Apache license
-* Homepage:  http://launchpad.net/dragonflow
-* Source: http://git.openstack.org/cgit/openstack/dragonflow
-* Bugs: http://bugs.launchpad.net/dragonflow
-* Documentation: http://docs.openstack.org/developer/dragonflow
+* Homepage:  https://launchpad.net/dragonflow
+* Source: https://git.openstack.org/cgit/openstack/dragonflow
+* Bugs: https://bugs.launchpad.net/dragonflow
+* Documentation: https://docs.openstack.org/developer/dragonflow
 
 .. image:: https://raw.githubusercontent.com/openstack/dragonflow/master/doc/images/df_logo.png
     :alt: Solution Overview
@@ -39,7 +39,7 @@ and more.
 This configuration is the current focus of Dragonflow.
 Overview and details are available in the `Distributed Dragonflow Section`_
 
-.. _Distributed Dragonflow Section: http://docs.openstack.org/developer/dragonflow/distributed_dragonflow.html
+.. _Distributed Dragonflow Section: https://docs.openstack.org/developer/dragonflow/distributed_dragonflow.html
 
 .. image:: https://raw.githubusercontent.com/openstack/dragonflow/master/doc/images/dragonflow_distributed_architecture.png
     :alt: Solution Overview