Only add -noprompt to TFS command-line when using TF everywhere.

Review Request #7143 — Created April 1, 2015 and discarded — Latest diff uploaded

Information

RBTools
release-0.7.x

Reviewers

The new tf.exe implementation of the command-line tools shipped in Visual
Studio 2013 Update 4 doesn't have a /noprompt argument. This change makes it so
we don't add that argument when we're using TF.exe

Verified that tf workfold no longer failed unconditionally.