Update topic icons and logos.
New meta icon and update to topics template
Larger icon for SN
Database updates for topic icon size and name
new devrandom
New science and security icons
new favicons
new zoo icons
fix  zoo icon alignment
fix whitespace.
set to default of our sn logo for now.

use chillax if we ever change the name of the repo.
Merge pull request #256 from paulej72/new-icons

New icons