Show supported versions for PC servers

The Minetrack daemon will send a different protocol version each time
it pings a server. If a server responds with the same protocol version,
it is assumed that the version is supported, and it is shown on the
page above the server's player count.

The list of versions to be tried is stored in config.json.
At the moment, 4 versions are checked:
- 4 (Minecraft 1.7.2)
- 5 (Minecraft 1.7.10)
- 47 (Minecraft 1.8)
- 107 (Minecraft 1.9)

assets/css/main.css

@@ -145,7 +145,7 @@ a {
 }
 
 .server > .column > .rank {
-    width: 64px; 
+    width: 64px;
     padding-top: 3px;
 }
 
@@ -157,6 +157,18 @@ a {
     margin-bottom: 2px;
 }
 
+.server > .column > .versions {
+	min-height: 22px;
+	padding-bottom: 3px;
+}
+
+.server > .column > .versions > .version {
+	padding: 1px 5px;
+    border-radius: 2px;
+    border: 1px solid #A09E9E;
+    font-size: 12px;
+}
+
 .category-header {
     margin-bottom: 10px;
     margin-left: 15px;
@@ -246,4 +258,4 @@ h3 {
 .button:hover {
     background: #ecf0f1;
     color: #3498db;
-}
+}