Test that cURL is installed

Per #273.
Eliminate port testing

It turns out that $_SERVER['SERVER_PORT'] is actually checking the
requested port, not the port that's served up. Vagrant translates 8080
requests to 80—Apache doesn't know anything about 8080—but SERVER_PORT
still reports that it's 8080. Disabling for now, will revisit when
addressing #275.

Per #273.
Suppress cURL output
Light cleanup
Only run the parser if the server environment is sane

Per #273.