Add Cosmo theme

MIT license from Bootswatch

application/views/user/add.php

@@ -114,6 +114,7 @@
                 <option value='default' selected="selected">Default</option>
                 <option value='blue'>Blue</option>
                 <option value='blue'>Dark</option>
+                <option value='cosmo'>Cosmo</option>
                 <option value='superhero'>Superhero (Dark)</option>
             </select>
         </div>

application/views/user/edit.php

@@ -94,6 +94,7 @@
                             <option value='default' <?php if($user_stylesheet == "default") { echo "selected=\"selected\""; } ?>>Default</option>
                             <option value='blue' <?php if($user_stylesheet == "blue") { echo "selected=\"selected\""; } ?>>Blue</option>
                             <option value='dark' <?php if($user_stylesheet == "dark") { echo "selected=\"selected\""; } ?>>Dark</option>
+                            <option value='cosmo' <?php if($user_stylesheet == "cosmo") { echo "selected=\"selected\""; } ?>>Cosmo</option>
                             <option value='superhero' <?php if($user_stylesheet == "superhero") { echo "selected=\"selected\""; } ?>>Superhero (Dark)</option>
                         </select>
                     </div>

assets/css/cosmo/overrides.css

@@ -0,0 +1,3 @@
+/*!
+ * No overrides for the default theme as it aligns with general.css
+*/