Clean up unused playground projects

Orleans.sln

@@ -229,8 +229,6 @@ Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "DashboardToy.Frontend", "pl
 EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "DashboardToy.AppHost", "playground\DashboardToy\DashboradToy.AppHost\DashboardToy.AppHost.csproj", "{84B44F1D-B7FE-40E3-82F0-730A55AC8613}"
 EndProject
-Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "DashboardToy.Common", "playground\DashboardToy\DashboardToy.Common\DashboardToy.Common.csproj", "{10F842A4-D5F9-41A7-B328-6D5A02BBE4C9}"
-EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -605,10 +603,6 @@ Global
 		{84B44F1D-B7FE-40E3-82F0-730A55AC8613}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{84B44F1D-B7FE-40E3-82F0-730A55AC8613}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{84B44F1D-B7FE-40E3-82F0-730A55AC8613}.Release|Any CPU.Build.0 = Release|Any CPU
-		{10F842A4-D5F9-41A7-B328-6D5A02BBE4C9}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
-		{10F842A4-D5F9-41A7-B328-6D5A02BBE4C9}.Debug|Any CPU.Build.0 = Debug|Any CPU
-		{10F842A4-D5F9-41A7-B328-6D5A02BBE4C9}.Release|Any CPU.ActiveCfg = Release|Any CPU
-		{10F842A4-D5F9-41A7-B328-6D5A02BBE4C9}.Release|Any CPU.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE
@@ -720,7 +714,6 @@ Global
 		{316CDCC7-323F-4264-9FC9-667662BB1F80} = {A41DE3D1-F8AA-4234-BE6F-3C9646A1507A}
 		{C4DD4F96-3EC6-47C6-97AA-9B14F0F2099B} = {316CDCC7-323F-4264-9FC9-667662BB1F80}
 		{84B44F1D-B7FE-40E3-82F0-730A55AC8613} = {316CDCC7-323F-4264-9FC9-667662BB1F80}
-		{10F842A4-D5F9-41A7-B328-6D5A02BBE4C9} = {316CDCC7-323F-4264-9FC9-667662BB1F80}
 	EndGlobalSection
 	GlobalSection(ExtensibilityGlobals) = postSolution
 		SolutionGuid = {7BFB3429-B5BB-4DB1-95B4-67D77A864952}