Support ALIAS records with Cloudflare (#89)

* simple facility for registering provider capabilities

* support for cloudflare. tests.

* js and docs

* docs

* generate

js/parse_tests/010-alias.js

@@ -0,0 +1,3 @@
+D("foo.com","none",
+    ALIAS("@","foo.com.")
+);

js/parse_tests/010-alias.json

@@ -0,0 +1,19 @@
+{
+		  "registrars": [],
+		  "dns_providers": [],
+		  "domains": [
+		    {
+		      "name": "foo.com",
+		      "registrar": "none",
+		      "dnsProviders": {},
+		      "records": [
+		        {
+		          "type": "ALIAS",
+		          "name": "@",
+		          "target": "foo.com."
+		        }
+		      ],
+		      "keepunknown": false
+		    }
+		  ]
+		}