Add timestamp to export-metadata
Add timestamp to export-metadata

Nick's export tool included a timestamp in the metadata, which
seems like a good idea.  This commit adds that to the clojure
export tool.

highb/puppetdb,wkalt/puppetdb,cprice404/puppetdb,johnduarte/puppetdb,puppetlabs/puppetdb,rbrw/puppetdb,cprice404/puppetdb,shrug/puppetdb,highb/puppetdb,mullr/puppetdb,melissa/puppetdb,senior/puppetdb,kbrezina/puppetdb,jantman/puppetdb,grimradical/puppetdb,melissa/puppetdb,rbrw/puppetdb,cprice404/puppetdb,senior/puppetdb,mullr/puppetdb,waynr/puppetdb,kbarber/puppetdb,waynr/puppetdb,wkalt/puppetdb,puppetlabs/puppetdb,highb/puppetdb,puppetlabs/puppetdb,kbrezina/puppetdb,ajroetker/puppetdb,highb/puppetdb,ajroetker/puppetdb,johnduarte/puppetdb,jantman/puppetdb,rbrw/puppetdb,jantman/puppetdb,johnduarte/puppetdb,ajroetker/puppetdb,puppetlabs/puppetdb,waynr/puppetdb,wkalt/puppetdb,mullr/puppetdb,shrug/puppetdb,grimradical/puppetdb,mullr/puppetdb,ajroetker/puppetdb,kbarber/puppetdb,puppetlabs/puppetdb,shrug/puppetdb,rbrw/puppetdb,melissa/puppetdb,mullr/puppetdb,johnduarte/puppetdb,kbrezina/puppetdb,grimradical/puppetdb,shrug/puppetdb,wkalt/puppetdb,kbarber/puppetdb,senior/puppetdb,kbarber/puppetdb,senior/puppetdb,waynr/puppetdb,grimradical/puppetdb,kbrezina/puppetdb,rbrw/puppetdb