Fix misparse of port when binding Unix socket

The hostname:port of URIs used in Minify are currently bogus and refer
to localhost only for historical reasons; there's no reason to retain
them and omitting them avoids generating an invalid URI when "port" is
not an integer.

Context: settings.port is passed to express's listen; if not numeric, it
is used a filename for a Unix domain socket.
This allows e.g. starting a server to be reverse-proxied on a multi-user
system, using the filesystem to handle access control and avoiding need
to allocate port numbers.

Before this change, etherpad-lite starts without error when configured
to listen on a Unix domain socket in this manner. However, `pad.js` and
`ace2_common.js` are generated incorrecting, causing an error
"Uncaught Error: The module at "ep_etherpad-lite/static/js/rjquery" does not exist."
when loading the editor:

When settings.port is a non-numeric string, e.g. `etherpad.sock`, a URI
of the form `http://localhost:etherpad.sock/static/js/rjquery.js` is
generated and parsed to find the file needed. In this case, the file
searched for is `:etherpad.sock/static/js/rjquery.js`, rather than the
expected `static/js/rjquery.js`. No such file exists, and the required
code is silently omitted from the bundle.

As a workaround, hard-code a (meaningless) hostname which can be parsed
correctly, since the current code makes no use of it anyway.

src/node/hooks/express/static.js

@@ -17,11 +17,12 @@ exports.expressCreateServer = function (hook_name, args, cb) {
 
   // Setup middleware that will package JavaScript files served by minify for
   // CommonJS loader on the client-side.
+  // Hostname "invalid.invalid" is a dummy value to allow parsing as a URI.
   var jsServer = new (Yajsml.Server)({
     rootPath: 'javascripts/src/'
-  , rootURI: 'http://localhost:' + settings.port + '/static/js/'
+  , rootURI: 'http://invalid.invalid/static/js/'
   , libraryPath: 'javascripts/lib/'
-  , libraryURI: 'http://localhost:' + settings.port + '/static/plugins/'
+  , libraryURI: 'http://invalid.invalid/static/plugins/'
   , requestURIs: minify.requestURIs // Loop-back is causing problems, this is a workaround.
   });
 

src/node/utils/Minify.js

@@ -264,7 +264,8 @@ function getAceFile(callback) {
     async.forEach(founds, function (item, callback) {
       var filename = item.match(/"([^"]*)"/)[1];
 
-      var baseURI = 'http://localhost:' + settings.port;
+      // Hostname "invalid.invalid" is a dummy value to allow parsing as a URI.
+      var baseURI = 'http://invalid.invalid';
       var resourceURI = baseURI + path.normalize(path.join('/static/', filename));
       resourceURI = resourceURI.replace(/\\/g, '/'); // Windows (safe generally?)