adoption of code for contrail webui from dsetia/devstack
Merge pull request #14 from shravani89/test-m1-build

adoption of code for contrail webui from dsetia/devstack
minor README update
update README
Support disabling services from localrc (eg. using disable_service)
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