Fixed bundling css files img relative path issue

Optimization bundling has an issue with css files that has img relative
path,
http://stackoverflow.com/questions/12577108/asp-net-mvc4-bundling-with-twitter-bootstrap
Added Web.Azure.config and UseBlobStorage setting

1. Added Azure configuration, set your conn strs to publish to azure
2. Added a web.config appSetting to toggle between using blob storage vs
file sys