Copy gp_mkpkg to obs service directory

Signed-off-by: Juha Kallioinen <juha.kallioinen@jollamobile.com>
Handle missing git clone target directory case

The script now creates a local gitpkg.tmp directory where it clones
the git repository in case the default path is not found.

Signed-off-by: Juha Kallioinen <juha.kallioinen@jollamobile.com>