Implemented support for installing `libcurl`

* Debian installs `libcurl3` and `libcurl4-openssl-dev`.
  Installing just `libcurl4-openssl-dev` would bring in
  `libcurl3`.  However, wanted others to know what my
  intentions were.
* RHEL installs `curl-devel`.  Not sure if this is the
  right package, but seems "right enough".

Fixes: #1