use svg for social link icons
update footer social icons with svg
Merge pull request #372 from G5/svg-social-links

Svg social links
Revert "Merge pull request #372 from G5/svg-social-links"

This reverts commit 8ae0738d6d726414e024b08aff3ad5df0670d77b, reversing
changes made to 6643f2bdd000e4e6cef780c879a76c6b72868135.
Merge branch 'master' into secure_prep