run godeps -t ./... as a test and ensure that dependencies.tsv agrees with what godeps outputs
We will look for godeps first in $PATH and then in $GOPATH/bin.  If it is not found, we'll skip the test.

Also make a windows-only dependency an all-OS dependency so godeps is always the same on all OSes.
Also fix up dependencies.tsv, since it was wrong.... showing why we need this test.