Check for PublishImageTag in VS land (#176)

Author: benvillalobos

packaging/build/Microsoft.NET.Build.Containers.targets

@@ -37,6 +37,7 @@
             <ContainerImageName Condition="'$(ContainerImageName)' == ''">$(AssemblyName)</ContainerImageName>
             <!-- Only default a tag name if no tag names at all are provided -->
             <ContainerImageTag Condition="'$(ContainerImageTag)' == '' and '$(ContainerImageTags)' == ''">$(Version)</ContainerImageTag>
+            <ContainerImageTag Condition="'$(RunningInVisualStudio)' == 'true' and '$(PublishImageTag)' != ''">$(PublishImageTag)</ContainerImageTag>
             <ContainerWorkingDirectory Condition="'$(ContainerWorkingDirectory)' == ''">/app</ContainerWorkingDirectory>
             <!-- Could be semicolon-delimited -->
         </PropertyGroup>