conditionally install wget if not present

Signed-off-by: Alfredo Deza <alfredo.deza@inktank.com>
Merge pull request #239 from alfredodeza/9265

conditionally install wget if not present
update the changelog

Signed-off-by: Alfredo Deza <alfredo.deza@inktank.com>
bump the version

Signed-off-by: Alfredo Deza <alfredo.deza@inktank.com>
1.5.15