Update Modulefile

If you do not have example42/git installed, then you will get the following error


Error: Puppet::Parser::AST::Resource failed with error ArgumentError: Invalid resource type git::reposync at /home/adaptive/.puppet/modules/elasticsearch/manifests/prerequisites.pp:28 on node sowenkibana.openstacklocal
Wrapped exception:
Invalid resource type git::reposync
Error: Puppet::Parser::AST::Resource failed with error ArgumentError: Invalid resource type git::reposync at /home/adaptive/.puppet/modules/elasticsearch/manifests/prerequisites.pp:28 on node sowenkibana.openstacklocal