unit: handle generator subscriptions earlier
doc: update README.md
doc: update client docs
Merge pull request #796 from bcwaldon/793

Reorder subscription management in UnitStateGenerator
Merge pull request #800 from bcwaldon/client-docs

Update fleetctl documentation
unit: testing UnitStateGenerator
Merge pull request #801 from bcwaldon/testUnitStateGenerator

unit: testing UnitStateGenerator
log: new logging package
*: switch from glog to fleet's log pkg
godep: drop glog
Merge pull request #802 from bcwaldon/new-logging

Get rid of glog
registry: fix comment typos

Also rename TestRegistry to FakeRegistry to reference the actual struct.
Merge pull request #803 from davidreynolds/master

registry: fix comment typos
agent: add global unit support to reconciler
agent: remove unnecessary TargetMachineID
engine: do not consider global units for scheduling
fleetctl: update to deal with global units

All fleetctl operations on global units are non-blocking. Updated
command descriptions to reflect this.

suToGlobal is shared across commands and so now moved to fleetctl.go

setTargetStateOfUnits should only care about DesiredState, not
CurrentState, of units it is attempting to modify.

Also standardises behaviour and error message reporting across commands
functional: various updates

Update to accommodate multiple UnitStates
Add a simple functional test for global units