Rework .travis.yml to work with new build env

Switched to 64 bit packages
Run tests unprivileged due to lack of cpanm as root on new env
Call openresty directly to avoid missing binary issues
Modify permissions on log dir to avoid permission errors running unprivileged

Signed-off-by: Ben Agricola <bagricola@squiz.co.uk>
Merge branch 'fix_travis' of github.com:benagricola/ledge into fix_travis