eg/tryhy: add server_sofware to welcome message

eg/tryhy/js/repl.js

@@ -25,7 +25,10 @@ $(document).ready(function(){
     animateScroll:true,
     promptHistory:true,
     autofocus:true,
-    welcomeMessage: 'hy ({hy_version})'.supplant({hy_version: hy_version})
+    welcomeMessage: 'hy ({hy_version}) [{server_software}]'.supplant({
+      hy_version: hy_version,
+      server_software: server_software
+    })
   });
   console.promptText('(+ 41 1)');
 });

eg/tryhy/main.hy

@@ -1,4 +1,5 @@
-(import [sys]
+(import [os]
+        [sys]
         [StringIO [StringIO]]
         [json]
         [hy.cmdline [HyREPL]]
@@ -22,7 +23,8 @@
 
 (with-decorator (kwapply (app.route "/") {"methods" ["GET"]})
   (fn []
-    (kwapply (render_template "index.html") {"hy_version" hy.__version__})
+    (kwapply (render_template "index.html")
+             {"hy_version" hy.__version__ "server_software" (get os.environ "SERVER_SOFTWARE")})
     ))
 
 (with-decorator (kwapply (app.route "/eval") {"methods" ["POST"]})

eg/tryhy/templates/index.html

@@ -8,6 +8,7 @@
     <script type="text/javascript" src="js/repl.js"></script>
     <script type="text/javascript">
       var hy_version = '{{hy_version}}';
+      var server_software = '{{server_software}}';
     </script>
     <link rel="stylesheet" type="text/css" href="css/style.css">
   </head>