*: add license header to all source files
Merge pull request #980 from jonboulle/license

*: add license header to all source files
fleetctl: handle -h/--help as cmd
doc: tweak API doc

- clean up style of headers, response codes, request formats
- move reference info (pagination, errors, etc) to end of doc
Merge pull request #968 from bcwaldon/851

Tweak API documentation
Merge pull request #981 from bcwaldon/977

fleetctl: handle --help as help cmd
docs: fix markdown formatting
systemd: unexport systemdUnitManager.UnitsDir
systemd: create lsUnitsDir & pkg.ListDirectory
systemd: add hashUnitFile(s)
systemd: preload unit hashes in NewSystemdUnitManager
Merge pull request #987 from bcwaldon/720

Preload systemdUnitManager hash cache
unit: drop old legacy payload code
Merge pull request #990 from bcwaldon/drop-legacy-code

unit: drop old legacy payload code
agent: compare unit hashes when reconciling

This incorporates hashes into the decision when agent reconciler is
calculating what tasks should be performed.