[WinPlat] Implementation of GetApplication for Windows Platform
Connected implementation of AssocQueryString module also present.
[WinPlat] Remove *itself* MD/XS from Open With List
Not allow an entry of MonoDevelop/Xamarin Studio to be present
in the Open With Right click Menu.
[WinPlat] Code Migration to Win32.cs
Assocation String, Association Flags enums shifted to Win32.cs
AssocQueryStringW shifted to Win32.cs
Merge pull request #583 from dipamchang/GetApplications

[WinPlat] Implementation of GetApplication for Windows Platform