implement 'address_info' wsapi that returns information about an email's...

implement 'address_info' wsapi that returns information about an email's current status.  who vouches for it, and if it's a secondary, is the email address known

lib/wsapi/address_info.js

+const
+db = require('../db.js'),
+primary = require('../browserid/primary.js');
+
+// return information about an email address.
+//   type:  is this an address with 'primary' or 'secondary' support?
+//   if type is 'secondary':
+//     known: is this address known to browserid?
+//   if type is 'primary':
+//     auth: what is the url to send the user to for authentication
+//     prov: what is the url to embed for silent certificate (re)provisioning
+
+exports.method = 'get';
+exports.writes_db = false;
+exports.authed = false;
+exports.args = ['email'];
+
+const emailRegex = /\@(.*)$/;
+
+exports.process = function(req, resp) {
+  // parse out the domain from the email
+  var email = url.parse(req.url, true).query['email'];
+  var m = emailRegex.exec(email);
+  if (!m) {
+    resp.sendHeader(400);
+    resp.json({ "error": "invalid email address" });
+    return;
+  }
+
+  primary.checkSupport(m[1], function(err, rv) {
+    if (err) {
+      logger.warn('error checking "' + m[1] + '" for primary support: ' + err);
+      resp.sendHeader(500);
+      resp.json({ "error": "can't check email address" });
+      return;
+    }
+
+    if (rv) {
+      rv.type = 'primary';
+      resp.json(rv);
+    } else {
+      db.emailKnown(email, function(known) {
+        resp.json({
+          type: 'secondary',
+          known: known
+        });
+      });
+    }
+  });
+};