apache::monitoring: provision 'links' package

`apache2ctl status` requires a package which provides `www-browser`.
cURLing /server-status gets you the raw HTML, which is not very readable.
Between links, lynx, and links2, links is the smallest and produces the most
readable text output (IMO).

Change-Id: I0aa356e0da032d024d279e6d973a6fb64d9c4375