Sysadmin: Make sure puppet won't re-install git in Ubuntu 11.10

Ubuntu 11.10 package manager is having too old git in it. We need
more recent version and install that by hand. This change prevents
puppet from re-installing the old version.

Change-Id: I1ef6f825592de534d235df858f8549e2a80b3930
Reviewed-by: Tony Sarajärvi <tony.sarajarvi@digia.com>