dotnet-build will produce a deps file for portable builds, and will now
create "runnable" outputs for RID-less targets
the outputs won't actually be runnable today because we need corehost
changes and to generate a deps.json file for corehost to use.
With this change, any referenced analyzer project will be parsed by the
project system and the assemblies will be passed down to the compiler.
By default, the analyzer language is considered to be "cs". If another
language is used, the "languageID" option should be specified inside the
"analyzerOptions" section of the project.json file.
Resolves#83
