If user has old version, redirect them to lbry.io/[os] to upgrade

The OS checking is ugly, but once we have an "upgrade" page on lbry.io we'll change it to point there

js/app.js

@@ -9,6 +9,15 @@ var App = React.createClass({
       viewingPage: window.location.search === '?settings' ? 'settings' : 'home'
     }
   },
+  componentWillMount: function() {
+    lbry.checkNewVersionAvailable(function(isAvailable) {
+      if (isAvailable) {
+        alert("The version of LBRY you're using is not up to date.\n\n" +
+              "You'll now be taken to lbry.io, where you can download the latest version.");
+        window.location = "http://www.lbry.io/" + (navigator.userAgent.indexOf('Mac OS X') != -1 ? 'osx' : 'linux');
+      }
+    });
+  },
   componentDidMount: function() {
     lbry.getStartNotice(function(notice) {
       if (notice) {

js/lbry.js

@@ -91,6 +91,18 @@ lbry.search = function(query, callback)
   lbry.call("search_nametrie", { "search": query }, callback);
 }
 
+lbry.checkNewVersionAvailable = function(callback) {
+  lbry.call('version', {}, function() {
+    // If the "version" method is available, we have a daemon new enough to do version checking
+    lbry.call('check_for_new_version', callback);
+  }, function(err) {
+    if (err.fault == 'NoSuchFunction') {
+      // If it's not available, we're definitely in an old version
+      callback(true);
+    }
+  });
+}
+
 //utilities
 lbry.formatCredits = function(amount, precision)
 {