Exclude shortcuts that are not available in currently active keyboard layout

This pull request goes with another one in Brackets shell repo and together they fix issue #8666.
i'm guessing these are keyboard identifiers as specified here http://msdn.microsoft.com/en-us/library/windows/desktop/ms646305(v=vs.85).aspx so "0409" for US English?  I don't think these numbers are static.  I think it's dependent on their load order