environs: remove VarDir global

worker/machiner/machiner.go

 package machiner
 
 import (
         "launchpad.net/juju-core/container"
         "launchpad.net/juju-core/log"
         "launchpad.net/juju-core/state"
         "launchpad.net/juju-core/state/watcher"
         "launchpad.net/tomb"
 )
 
 // NewMachiner starts a machine agent running that
 // deploys agents in the given directory.
 // The Machiner dies when it encounters an error.
 func NewMachiner(machine *state.Machine, dataDir string) *Machiner {
         cont := &container.Simple{DataDir: dataDir}
         return newMachiner(machine, cont)
 }
 
 func newMachiner(machine *state.Machine, cont container.Container) *Machiner {
         m := &Machiner{localContainer: cont}
         go m.loop(machine)
         return m
 }
 
 // Machiner represents a running machine agent.
 type Machiner struct {
-        tomb      tomb.Tomb
+        tomb           tomb.Tomb
         localContainer container.Container
 }
 
 func (m *Machiner) loop(machine *state.Machine) {
         defer m.tomb.Done()
         w := machine.WatchUnits()
         defer watcher.Stop(w, &m.tomb)
 
         // TODO read initial units, check if they're running
         // and restart them if not. Also track units so
@@ skipping 29 matching lines @@
 // Wait waits until the Machiner has died, and returns the error encountered.
 func (m *Machiner) Wait() error {
         return m.tomb.Wait()
 }
 
 // Stop terminates the Machiner and returns any error that it encountered.
 func (m *Machiner) Stop() error {
         m.tomb.Kill(nil)
         return m.tomb.Wait()
 }