Update build-core.proj

Author: mythz

build/build-core.proj

@@ -12,6 +12,7 @@
   <PropertyGroup>
     <BuildSolutionDir>$(MSBuildProjectDirectory)/..</BuildSolutionDir>
     <SrcDir>$(BuildSolutionDir)/src</SrcDir>
+    <TestsDir>$(BuildSolutionDir)/tests</TestsDir>
     <Configuration Condition="$(Configuration) == ''">Release</Configuration>
     <NuGetPackageDir>$(BuildSolutionDir)/NuGet/</NuGetPackageDir>
     <PackageVersion>$(MajorVersion).$(MinorVersion).$(PatchVersion)</PackageVersion>
@@ -40,6 +41,7 @@
   <!-- need to remove old caches from nuget restore from .Core csproj's -->
   <Target Name="ClearNuGetRestoreCaches">
     <RemoveDir Directories="$(SrcDir)/ServiceStack.Aws/obj" />
+    <RemoveDir Directories="$(TestsDir)/ServiceStack.Aws.DynamoDbTests/obj" />
   </Target>
 
   <Target Name="UpdateVersion">