doc: add versioning information for template/global units
Merge pull request #858 from jonboulle/doc

doc: add versioning information for template/global units
Documentation: Fix template link in service files

In the Service Files section of https://coreos.com/docs/launching-containers/launching/fleet-example-deployment/
there is a link to templates which points at a Github link that 404's.
Merge pull request #842 from dpetzel/doco_fix

Fix link to templates on fleet example page.
log: add EnableTimestamps
fleetctl: enable timestamp logging

Fix #847
log: manually construct header