Incorrect version tag displayed when running SHARPy

[ngoiz]

The version tags we have been using are lightweight tags and, hence, when running

def get_git_tag(di=sharpydir.SharpyDir):
    return subprocess.check_output(['git', 'describe'], cwd=di).strip().decode('utf-8')

it returns v0.1 instead of the correct version.

For future releases we need to ensure the tags are annotated tags.