Request: defaults for `dotnet lambda package` (-c Debug and -f netcoreapp1.0 or empty if 1 target)

[FLGMwt]

It seems that it's common for first-class dotnet verbs such as publish and build to default --configuration to Debug. I think it would make sense for dotnet lambda package to do the same.

Additionally, it would be nice to allow for --framework to be optional when only one TargetFramework is defined in the project. publish handles this without arguments. And is it meaningful to have a lambda project with two target frameworks?

[normj]

I was nervous about adding any defaults in the tooling especially while the project system is going through such big changes. That was one of the reasons for the aws-lambda-tools-defaults.json file so that the defaults would reside with the code and not in the tooling.