fix(#4): build target uri for windows

[616b2f]

resolve #4

[schinnerld]

Two unit tests are still failing.

1. RequestBuildTargetCompile_ForProjectWithErrors_Success (testcase 1)
   "C:\C:\Git..AspNet.Example.sln" can't be loaded
   Fixed in \src\bsp4csharp\Protocol\BuildTargetIdentifier.cs / Ln 13
   => return Uri.ToString().Replace("file://", "").TrimStart('/');
2. RequestBuildTargetCompile_ForProjectWithErrors_Success (testcase 2)
   does not work under German language Windows
   Fixed in \test\BuildServerProtocolTests.cs / Ln 67
   => [InlineData(TestProject.AspnetWithRestoreErrors, "(>= 998.0.5)", 2)]

[616b2f]

@schinnerld could you try again pls

[schinnerld]

On my Windows system, all unit tests run without errors with these changes.