Convert to Uri

UriBuilder provides access to the query portion, and intelligently adds the question mark.
Create UriExtensions.cs
Update UriExtensions.cs
Update Listing.cs
Update AuthProvider.cs

Changed flags to Uppercase, add .tolower on implementation. (it's ugly, but it works). Change to UriService uris.
Add Uri Methods
Add Uri Methods

Also made obsolete the older methods
Create UriService.cs
Specify Obsolescence
Specify Obsolescence
Add Endpoints enum and GetUri
Change to Enum Attribute technique
Make UriService Internal
Merge pull request #107 from Erok21/master

UriService and Uri changeover infrastructure