upgraded stevedore package in download_python_dependencies
added the code for the dynamic updation of dns in replace_irond_basic_auth_users
CI support to download redis-server,zookeeper,ncclient with fetch_packages.py
added installer.xml to download packages using fetch_packages.py instead of wget
modified function is_service_enabled in functions file
Merge pull request #13 from ravitejagettam/test-m1-build

upgraded stevedore package in download_python_dependencies