Previously the raw time difference was used which includes the network trip time
between the node and the ntp server. This makes setting alerts off the value
troublesome as it depends on the latency as well as the clock offset.
This puts all collector-specific flags into their own namespace under
"collector.<collector-name>", and moves from camel case to dashes, which
is the standard in Prometheus land now.
Switch to Update using the Collecter Collect interface, due to not knowing all
metricnames in all modules beforehand we can't use Describe and thus the full
Collecter interface.
Remove 'updates', it's meaning varies by module and doesn't add much.
Johannes 'fish' Ziemke