start Android version
Merge branch 'develop' of github.com:ioklo/DCView into develop
Import WatermarkTextBox (https://github.com/JoshClose/WindowsPhoneControls/) for bug fix
fix TargetType from WatermarkTextBox to TextBox
Factory 추가
Refactoring

 - Use HttpClient instead of HttpWebRequest
 - Remove Can- prefix methods from IBoard, IArticle interface
 - Add [NotSupported] attribute to annotate the not supported method
 - Add DeleteArticle feature