(PDB-1389) Add puppet-agent option for debian dependencies
(PDB-1389) Add puppet-agent option for debian dependencies

Previously installing the puppet-agent and puppetdb together would not
work on debian/ubuntu because puppetdb requires a specific version of
puppet or puppet-common, which puppet-agent cannot provide. This commit
addresses that by allowing puppet-agent to be a fallback if
puppet/puppet-common is not available (puppet for puppetdb,
puppet-common for the terminus).

rbrw/puppetdb,ajroetker/puppetdb,ajroetker/puppetdb,grimradical/puppetdb,mullr/puppetdb,waynr/puppetdb,kbarber/puppetdb,highb/puppetdb,kbrezina/puppetdb,rbrw/puppetdb,rbrw/puppetdb,wkalt/puppetdb,shrug/puppetdb,kbrezina/puppetdb,highb/puppetdb,rbrw/puppetdb,puppetlabs/puppetdb,wkalt/puppetdb,waynr/puppetdb,shrug/puppetdb,senior/puppetdb,kbarber/puppetdb,ajroetker/puppetdb,puppetlabs/puppetdb,waynr/puppetdb,kbarber/puppetdb,senior/puppetdb,kbarber/puppetdb,kbrezina/puppetdb,wkalt/puppetdb,mullr/puppetdb,rbrw/puppetdb,shrug/puppetdb,waynr/puppetdb,grimradical/puppetdb,ajroetker/puppetdb,highb/puppetdb,mullr/puppetdb,puppetlabs/puppetdb,mullr/puppetdb,senior/puppetdb,wkalt/puppetdb,shrug/puppetdb,puppetlabs/puppetdb,mullr/puppetdb,grimradical/puppetdb,kbrezina/puppetdb,grimradical/puppetdb,puppetlabs/puppetdb,highb/puppetdb,senior/puppetdb