stylesheets: rename *.css.scss -> *.scss.

Fixes "DEPRECATION WARNING: Extra .css in SCSS file is unnecessary."

app/assets/stylesheets/common/user_styles.scss

@@ -0,0 +1,31 @@
+a.user-admin.with-style {
+  color: red;
+}
+
+a.user-moderator.with-style {
+  color: orange;
+}
+
+a.user-janitor.with-style {
+  color: green;
+}
+
+a.user-contributor.with-style {
+  color: purple;
+}
+
+a.user-builder.with-style {
+  color: #6633FF;
+}
+
+a.user-platinum.with-style {
+  color: gray;
+}
+
+a.user-gold.with-style {
+  color: #0000FF;
+}
+
+a.user-member.with-style {
+  color: auto;
+}