Add season codes and overview page.

templates/editseason.html

@@ -14,6 +14,14 @@
            value="{{ model['id'] }}"
            readonly>
   </div>
+  <div class="form-group">
+    <label for="code">Season Code</label>
+    <input name="code"
+           type="text"
+           class="form-control"
+           id="code"
+           value="{{ model['code'] }}">
+  </div>
   <div class="form-group">
     <label for="game">Game Name</label>
     <input name="game"