Add some content, images, and give proper credits.
On branch master, changes to be committed:
	modified:   Linux_intro_presentation.odp
	modified:   distro_logos/sources_and_credits.md
	new file:   tux/Tux-G2.svg
	new file:   tux/Tux.png
	new file:   tux/sources_and_credits.md
Correct some content and add slide effects.
On branch master, changes to be committed:
	modified:   Linux_intro_presentation.odp