chore(makefile) improve install and dev targets
chore(makefile) improve install and dev targets

- install now properly takes its `OPENSSL_DIR` flag, as it should be
  when installing luasec via Luarocks
- better check for installed developement modules

ccyphers/kong,jebenexer/kong,beauli/kong,Kong/kong,icyxp/kong,salazar/kong,jerizm/kong,li-wl/kong,Kong/kong,Mashape/kong,akh00/kong,Vermeille/kong,Kong/kong,shiprabehera/kong