This setup will now correctly set the version number from the git tag.
When using `--version`, we will see the binary name, the package it was
built from and a git hash based on the tag:
```console
$./bin/dist -v
./bin/dist github.com/docker/containerd 0b45d91.m
```
Note that in the above example, if we set a tag of `v1.0.0-dev`, that
will show up in the version number, as follows:
```console
$./bin/dist -v
./bin/dist github.com/docker/containerd v1.0.0-dev
```
Once commits are made past that tag, the version number will be
expressed relative to that tag and include a git hash:
```console
$./bin/dist -v
./bin/dist github.com/docker/containerd v1.0.0-dev-1-g7953e96.m
```
Some these examples include a `.m` postfix. This indicates that the
binary was build from a source tree with local modifications.
We can add a dev tag to start getting 1.0 version numbers for test
builds.
Signed-off-by: Stephen J Day <stephen.day@docker.com>
