Update DataDog API key only if it changed
Update DataDog API key only if it changed

( Also, use consulate to manipulate KV in a cleaner fashion )

Fixes #194

Nubisproject/nubis-consul,Nubisproject/nubis-consul,tinnightcap/nubis-consul,gozer/nubis-consul,limed/nubis-consul,tinnightcap/nubis-consul,Nubisproject/nubis-consul,gozer/nubis-consul,limed/nubis-consul,gozer/nubis-consul