Merge pull request #150 from dougm/device-helpers

Add NetworkReference interface
Move govc/test Vagrant boxes

- move esxbox to its own directory

- move vcsim from contrib to test
Merge pull request #152 from dougm/govc-test

Move govc/test Vagrant boxes
Answer pending VM questions from govc
Merge pull request #153 from pietern/question

Answer pending VM questions from govc
Simplify vcsim_env helper
Default vcsim box to 4G memory
Fix network device.remove test
Add wrapper to manually run govc against vcsim
Add network flag required test

Plenty of tests already cover the case where we default to the single
"VM Network" in esxbox.
Test that -net flag is required when there are multiple
networks.
Add default GOVC_HOST to vcsim_env
Add host bats test

Mainly for HostSystemFlag/lister coverage.
Add ls bats test
Fix HostSystem.ResourcePool with cluster parent
Merge pull request #154 from dougm/govc-test

Add find/list helper related bats tests
mv govc/flags/list -> govmomi/list
Add vm.info bats test
Move govc resource finders to govmomi/find package
Merge pull request #155 from dougm/finder

Move find/list helpers from govc to govmomi
Add VirtualDeviceList FindByBackingInfo method