Cannot `dotnet build` with multiple fsproj in same dir

[enricosada]

Having a directory who contains multiple fsproj (lib1.fsproj, lib2.fsproj)

• dotnet restore lib1.fsproj works

• dotnet build lib1.fsproj fails with error

  CoreCompile:
      dotnet compile-fsc @e:\repro\obj\Debug\netstandard1.6\dotnet-compile.rsp
      Specify which project file to use because this 'e:\repro' contains more than one project file.
  1>C:\Users\{user}\.nuget\packages\fsharp.net.sdk\1.0.0-alpha-000009\build\netstandard1.0\FSharp.NET.Core.Sdk.targets(131,9): error MSB3073: The command "dotnet compile-fsc @e:\repro\obj\Debug\netstandard1.6\dotnet-compile.rsp" exited with code 1. [e:\repro\lib1.fsproj] [e:\repro\lib1.fsproj]     
  

test added with #46 in test-msbuild/TestMultipleLibraryInSameDir

Why: atm the F# dotnet build use the dotnet-compile-fsc tool, but the sdk doesnt support invoking tools if multiple *proj exists in same directory.

Workaround: until #25 is ready (if is enough), move the fsproj in another directory.

[enricosada]

Fixed by #61 , removing the need of use dotnet-compile-fsc tool