Allow overriding shared_dir
Allow overriding shared_dir

Signed-off-by: Julien Pivotto <df1ed88a312a603dfee9f157a90fa8f7f195ab59@inuits.eu>

mdebruyn-trip/puppet-prometheus,bastelfreak/puppet-prometheus2,bastelfreak/puppet-prometheus2,bastelfreak/puppet-prometheus2,dhoppe/puppet-prometheus,dhoppe/puppet-prometheus,mdebruyn-trip/puppet-prometheus,dhoppe/puppet-prometheus,mdebruyn-trip/puppet-prometheus