Keep Curl Bootstrap Working With http:// (#3113)

* Add comments documenting problems in recent versions of NetCDF.
* Add comments to packages required to install curl.

var/spack/repos/builtin/packages/openssl/package.py

@@ -33,6 +33,7 @@ class Openssl(Package):
        Layer Security (TLS) and Secure Sockets Layer (SSL) protocols.
        It is also a general-purpose cryptography library."""
     homepage = "http://www.openssl.org"
+    # URL must remain http:// so Spack can bootstrap curl
     url      = "http://www.openssl.org/source/openssl-1.0.1h.tar.gz"
     list_url = "https://www.openssl.org/source/old/"
     list_depth = 2