update sign script
update sign script

For convenience, use push and pop location.  Update the path to sign
tool.  It would be better to derive this location, but apparently that's
harder than expected.

Signed-off-by: Jamie Couture <b4dde37aa2aac745c0e6c43447507eaeace3e59f@quandl.com>

quandl/quandl-excel-windows