Update README to improve scripted install instructions
Update README to improve scripted install instructions

The raw URLs were missing the /master branch

The last command was confusing if you don't know the
meaning of the positional parameters

phchoic/puppet_openstack_builder,CiscoSystems/puppet_openstack_builder,michaeltchapman/puppet_openstack_builder,CiscoSystems/puppet_openstack_builder--to-be-deleted,michaeltchapman/vagrant-consul,CiscoSystems/openstack-installer--to-be-replaced-by-puppet_openstack_builder,michaeltchapman/vagrant-consul,michaeltchapman/puppet_openstack_builder,CiscoSystems/puppet_openstack_builder,CiscoSystems/puppet_openstack_builder--to-be-deleted,phchoic/puppet_openstack_builder,phchoic/puppet_openstack_builder,CiscoSystems/openstack-installer--to-be-replaced-by-puppet_openstack_builder,CiscoSystems/openstack-installer--to-be-replaced-by-puppet_openstack_builder,CiscoSystems/puppet_openstack_builder--to-be-deleted,michaeltchapman/puppet_openstack_builder