BuildRelease.ps1 require tf command to build

[kant2002]

BuildRelease.ps1 file requires that tf command should be in the path. This is no longer needed since NodeJS tools now on the GitHub instead of CodePlex.

[mousetraps]

We're actually not 100% off tfs. The GitHub repo is the source of truth, but we're mirroring everything back into TFS so that our internal test machines can continue to run.