Use package license expression and fix icon

Rx.NET/Source/Directory.build.props

@@ -4,11 +4,10 @@
     <MinClientVersion>2.12</MinClientVersion>
     <GenerateDocumentationFile>true</GenerateDocumentationFile>
     <Authors>.NET Foundation and Contributors</Authors>
-    <PackageIconUrl>http://go.microsoft.com/fwlink/?LinkId=261274</PackageIconUrl>
+    <PackageIconUrl>https://raw.githubusercontent.com/dotnet/reactive/0f837d11385cfaf575861ccc5a5fbcafb22d888f/Rx.NET/Resources/Artwork/Logo.png</PackageIconUrl>
     <PackageProjectUrl>https://github.com/dotnet/reactive</PackageProjectUrl>
-    <PackageLicenseUrl>http://go.microsoft.com/fwlink/?LinkID=261272</PackageLicenseUrl>
-    <PackageRequireLicenseAcceptance>true</PackageRequireLicenseAcceptance>    
-    <DebugType>embedded</DebugType>
+    <PackageLicenseExpression>Apache-2.0</PackageLicenseExpression>
+    <DebugType Condition="'$(Configuration)' != 'Debug'">embedded</DebugType>
     <SignAssembly>true</SignAssembly>
     <AssemblyOriginatorKeyFile>$(MSBuildThisFileDirectory)ReactiveX.snk</AssemblyOriginatorKeyFile>
     <NoWarn>$(NoWarn);1701;1702;CS1591;NU5105</NoWarn>