Update neutron content for Juno

I updated the neutron content in the installation guide for Juno
as follows:

1) For RHEL/CentOS/Fedora, added 'which' to list of packages to
   install on controller node because of a dependency not
   managed by the python-neutronclient package.
2) Added line breaks to init script workaround to improve
   readability.
3) Fixed incorrect init script name on compute node.

Change-Id: Ide38d428e79b182e2f1d749d2580b51e7d81bd72
Merge "Update neutron content for Juno"