Add package info, make guide openSUSE version independent

Add information about OpenStack packages for Ubuntu and
openSUSE.

Update openSUSE information, remove FIXMEs for openSUSE where nothing
needs to be done.

Remove some Ubuntu specific instructions that do not apply from
section_dashboard-system-reqs.xml.

Don't mention openSUSE version in titles etc (like Fedora guide does).

Change-Id: I68dea39441afc6bf5271672ccf35429893591965