Update README.md
Update README.md
Added GetDialogUrl method
Added GetDialogUrl unit tests. Automatically include app_id or client_id in dialog url.
Merge pull request #238 from ntotten/getdialogurl

Added GetDialogUrl method
Version to 6.3.1
Updated nuget package description
Version to 6.3.2
Version to 6.3.2
Added ParseDialogCallbackUrl method.
Changed ParseDialogCallbackUrl method to use default serializer.
Merge pull request #240 from ntotten/parsedialogcallback

Added ParseDialogCallbackUrl method
Version to 6.4.0
Updated assembly info.
Removed BUILD image.
Merge pull request #253 from facebook-csharp-sdk/dev

Removed BUILD image.
Updated site url.
Merge pull request #254 from facebook-csharp-sdk/dev

Updated site url.
Internals visible to Facebook.Client
Merge pull request #260 from ntotten/internals

Internals visible to Facebook.Client. Closes #256.