Revert "change udacity tiles to pictures"

This reverts commit 392ba3a5dadb861f0d75227aba4eb493d57f1b98.

Conflicts:
	style/main.css
Revert "change udacity tiles to pictures"

This reverts commit 392ba3a5dadb861f0d75227aba4eb493d57f1b98.

Conflicts:
	style/main.css