add Slider component

add Slider component

src/styles/mixins/button.less

@@ -120,7 +120,7 @@
     border: 1px solid transparent;
     white-space: nowrap;
     line-height: @line-height-base;
-    user-select: none;
+    .user-select();
     .button-size(@btn-padding-base; @btn-font-size; @btn-border-radius);
     .transform(translate3d(0, 0, 0));
     //.transition(all @transition-time linear);

src/styles/mixins/common.less

@@ -12,4 +12,10 @@
     &::-webkit-input-placeholder {
         color: @color;
     }
+}
+
+.user-select(@type: none) {
+    -webkit-user-select: @type;
+    -moz-user-select: @type;
+    user-select: @type;
 }