Unify distribution versions for Install Guide

Add version numbers for RHEL, CentOS, Fedora, openSUSE and SLES to
Install Guide.
Do not use codename for Debian in title and remove LTS from Debian
version.
Use version 7 for Debian.
Add missing text for SLES in intro.

Update Juno and trunk index pages and common appendix for the change.

Change-Id: Ie3938679f9a457aba7f71eda7911905aaa6659ef