add a selectTheme button (cannot select now) for nature-theme to customize/theme

lib/views/admin/customize.html

@@ -65,6 +65,11 @@
                 data-theme="{{ webpack_asset('style-theme-default-dark').css }}">
               {% include 'widget/theme-colorbox.html' %}
             </a>
+            <a id="theme-option-nature"
+             class="nature"
+             data-theme="{{ webpack_asset('style-theme-nature').css }}">
+              {% include 'widget/theme-colorbox.html' %}
+            </a>
           </div>
 
           <div class="form-group">

resource/styles/agile-admin/inverse/colors/nature.scss

@@ -0,0 +1,21 @@
+@import '../variables';
+
+$themecolor:#112744;
+
+$topbar:#334455;
+$sidebar:#fff;
+$bodycolor:#fff;
+$headingtext: #2b2b2b;
+$bodytext: #333333;
+$linktext: lighten($themecolor, 20%);
+$linktext-hover: lighten($linktext, 20%);
+$sidebar-text:#38495a;
+
+$primary: $themecolor;
+
+$logo-mark-fill: lighten(desaturate($topbar, 10%), 15%);
+$wikilinktext: lighten($themecolor, 20%);
+$wikilinktext-hover: lighten($wikilinktext, 20%);
+
+@import 'apply-colors';
+@import 'apply-colors-light';

resource/styles/scss/_admin.scss

@@ -116,5 +116,16 @@
         fill: #f75b36;
       }
     }
+    .nature {
+      .color1 {
+        fill: #dfffd1;
+      }
+      .color2 {
+        fill: #1f9b33;
+      }
+      .color3 {
+        fill: #56f736;
+      }
+    }
   }
 }