Remove the commit column on our download page

As required by the ASF moderator.

However first please fix the download page so it does not link to the Git
repo.
Please drop the commit id and the link; they are not appropriate for a
download page.

Only approved releases should be linked from the download page.

Whilst the commit itself may have been included in the VOTE email as part
of the approval process, it is not a formal release artefact. And links to
repos give access to code that has not been approved.

Information on commit ids and git repos etc should appear on pages intended
for the HBase developer community only.