fix main SCSS file paths

Fixes 2916ac43 errata
FYI @glebm

bower.json

@@ -14,7 +14,7 @@
   ],
   "homepage": "http://getbootstrap.com",
   "main": [
-    "sass/_bootstrap.scss",
+    "scss/_bootstrap.scss",
     "dist/css/bootstrap.css",
     "dist/js/bootstrap.js"
   ],

package.json

@@ -17,7 +17,7 @@
     "test": "grunt test"
   },
   "style": "dist/css/bootstrap.css",
-  "sass": "_sass/bootstrap.sass",
+  "sass": "scss/_bootstrap.scss",
   "main": "./dist/js/npm",
   "repository": {
     "type": "git",