Getting UnauthorizedAccessException on NamedPipeClientStream.TryConnect when using booster

[Jand42]

Reproduce:

• Run ./build CI-Release
• Modify and build a project from VS

Seems like the WS-Stop target is somehow to blame, aggressively killing pipe will mess with its discoverability later. Still not clear on the details. But here is a working plan to reduce headaches:

• run the WS-Stop build step only for core (also, modify to kill the booster that's running from under current directory only)
• fall back to Standalone build for any unexpected failure
• for core only, testing if restarting the booster one more time automatically at the end of the FAKE build process resolve development annoyances on core itself