Add FollowSymLinks option to /images .htaccess rule

This makes sure that thumbnails load properly. Apparently
(in OSX at least), if you don't have FollowSymLinks or
SymLinksIfOwnerMatch on, loading thumbnails gives a 500
error with the existing rewrite rules in place.

Bug: 62289
Change-Id: Icc812fcf9a0b821d2ad84359e5c1d8fb8e9c78a0