fix(webpack): fix peerDependencies for css loaders (#2131)

fixes #2130

Author: Awk34

Diff for: templates/app/_package.json

@@ -131,10 +131,13 @@
     "raw-loader": "^0.5.1",
     "style-loader": "^0.13.0",
     <%_ if(filters.sass) { _%>
+    "node-sass": "^3.8.0",
     "sass-loader": "^3.1.1",<% } %>
     <%_ if(filters.less) { _%>
+    "less": "^2.7.1",
     "less-loader": "^2.2.3",<% } %>
     <%_ if(filters.stylus) { _%>
+    "stylus": "^0.54.5",
     "stylus-loader": "^2.1.1",<% } %>
     "karma-webpack": "^1.7.0",
     <%# END WEBPACK %>