Dev builds for debian packages previously had system time inserted into
their packaging names while both static and rpm builds instead had the
git commit time.
This commit remedies that by pushing the generation of the debian
package version into a separate script to mirror what is being done in
static and rpm builds.
To give you an idea of what it looks like take the following examples:
```
❯ ./gen-deb-ver ~/work/docker-ce/components/engine/ $(cat ~/work/docker-ce/VERSION)
18.03.0~ce~dev~git20180202.170651.0.e232737
```
```
❯ ./gen-rpm-ver ~/work/docker-ce/components/engine $(cat ~/work/docker-ce/VERSION)
18.03.0.ce 0.0.dev.git20180202.170651.0.e232737 e232737
```
```
❯ ./gen-static-ver ~/work/docker-ce/components/engine/ $(cat ~/work/docker-ce/VERSION)
18.03.0-ce-dev-20180202.170651-e232737
```
Signed-off-by: Eli Uriegas <eli.uriegas@docker.com>
Upstream-commit: 23e3e42df6cb4e5cafd8648344ad37de25002971
Component: packaging
b87196602b