Release Google.Api.CommonProtos 1.4.0

This release:

- Contains the latest common protos
- Updates the Google.Protobuf dependency to 3.6.1
- Contains manual enhancements for Money and Date

Google.Api.CommonProtos/Google.Api.CommonProtos.csproj

@@ -3,7 +3,7 @@
   <Import Project="..\CommonProperties.Production.xml" />
 
   <PropertyGroup>
-    <VersionPrefix>1.3.0</VersionPrefix>
+    <VersionPrefix>1.4.0</VersionPrefix>
     <TargetFrameworks>netstandard1.3;net45</TargetFrameworks>
   </PropertyGroup>