Revert "Add support for using HttpContextBase, HttpRequestBase, HttpResponseBase."

This reverts commit 0c09345d9607aeea070a91db1ebc1ad172a2330e.
Revert "Add a reference to System.Web.Abstractions if using HttpRequestBase/HttpResponseBase"

This reverts commit 9c5ed0236c40ff625cbfb634c5960b192bc443ec.