Change Watch Timeout to Seconds

Seems like a good idea to have all the Etcd client calls in seconds, I
got caught out by the watch value using Milliseconds.
Added Support for Admin Machine Endpoint

I needed this for my project and added it in a similar way to the
Statistics endpoint.
Merge branch 'machine-endpoint' of git://github.com/james-andrewsmith/etcetera into james-andrewsmith-machine-endpoint
adding test to machine module