Fix Markdown image references

Pandoc does not fully follow Markdown syntax in that the Alt text is
always rendered as an image caption. Since that is distracting, remove
the alt text altogether.
Add TODO item for info about Florian
Fix formatting, section headings, bullets and grammar glitches
Fix formatting and content in section on Ceph
Fix content and formatting in section on HA networking and OpenStack services
Run pandoc with --slide-level 2

Make the #2 heading level ("##") the default for normal slides,
creating title slides for #1 headings ("#").
add img folder & change image path`s