add web api client libs

Redistributable DLL files. You may copy and distribute the object code
form of the following files.

·   System.Net.Http.dll

·   System.Net.Http.Formatting.dll

·   System.Web.Http.SelfHost.dll

·   System.Web.Http.WebHost.dll

·   System.Web.Http.dll

·   System.Net.Http.WebRequest.dll

·   System.Web.Mvc.dll
added code to download an image