Debugger: Cannot specify configuration, that is debugger always loads ../bin/Debug/*/whatever.dll

## Environment data

`dotnet --info` output:

```
.NET Command Line Tools (1.0.0-preview2-003121)

Product Information:
Version: 1.0.0-preview2-003121
Commit SHA-1 hash: 1e9d529bc5

Runtime Environment:
OS Name: Mac OS X
OS Version: 10.11
OS Platform: Darwin
RID: osx.10.11-x64
```

VS Code version:

```
1.2.1
```

C# Extension version:

```
1.2.1
```

I have some tests that fail only on osx and linux in release builds running on CoreCLR. I cannot get the debugger to attach to release artifacts in ../bin/Release/netcoreapp1.0/ folder.

I have to tried to make 'build' task only build configuration=Release. But 'codelens' run test and debug test, seems always to run tests with configuration=Debug. And I cannot get F5-debugging to work with this canonical './src/library', '/.test/library.tests' repo tree.

I have commited .vscode folder together with the rest of my code [here](https://github.com/maxild/Skat/tree/dotnetcli/.vscode)

task 'failingtest' is a failing test (-method switch shows test method) that I cannot debug with the omnisharp debugger extension.

Related to #455, especially this [comment](https://github.com/OmniSharp/omnisharp-vscode/issues/455#issuecomment-227294561)