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