fix: add back Bower dependencies

Bower dependencies in `bower.json` were removed in #11073 in the migration from Bower to npm.

These dependencies should not have been removed as the Bower package still require `jquery` and `what-input`. Someone installing `foundation-sites` with bower should still have these packages included. We simply don't use Bower anymore in development mode and don't promote its usage in the documentation.

Removing `bower install` commands was sufficiant for this migration and Bower dependencies in `bower.json` were unrelated.

See #11073

bower.json

@@ -31,6 +31,10 @@
     "type": "git",
     "url": "https://github.com/zurb/foundation-sites"
   },
+ "dependencies": {
+   "jquery": ">=2.2.0",
+   "what-input": ">=4.1.0"
+  },
   "ignore": [
     ".babelrc",
     ".browserslistrc",