This includes a bugfix to the cty/msgpack package to ensure correct
decoding of unknown and null values.
This also includes updates to cty's dependencies.
A number of PRs have come through which modified the vendor folder
without recording the proper information. This resets everything back to
the recorded version.
Previous deps merge had been captured by an older version of godep,
updating godep and rerunning...
godep save $(go list ./... | grep -v /vendor/)
...yielded this diff.
New `godep` also produced a warning to pin to the major Go version
instead of the minor one, which we do here as well.