new(feat): added collector for chrony time offsets (ntp time skew)

Change-Id: If4863300ed483dcd83280dfe5c6d668eeacad530
fix(feat): removed internal time unit conversion, now using the diamond one

Change-Id: Ibf52200bf05baa1dc5cce2f82284aeea85d5eb80
fix(feat): removed dead code

Change-Id: I5ecbcd6ad1c691de1298506996b9cd176414e9e7
Merge pull request #663 from rtoma/chronyd

new(feat): added collector for chrony time offsets (ntp time skew)