Merge pull request #1374 from jblaine/patch-1

Be more helpful with vboxmanage_error
Retry SSH on EADDRINUSE
Remove V2 forwarded ports config because it is unused
Merging networks works again
Get rid of unused variable
`vagrant package` works again
Hooks allow parameters and blocks to middlewares
action_hooks can hook into specific actions
Specify action_name for all machine actions for action hooks
Environment#hook allows hooks to be run at arbitrary points
environment_unload hook
Better logging around environment hooks
Be smarter about determining if plugin load failed
Always log the exception raised when error loading a plugin
The hook callable has to be an Action builder so the hooks are called
For hooks, put the environment in the action env
Retry setting default name for VirtualBox VM [GH-1368]
Only look for `Vagrantfile` if no more specific was given
VAGRANT_VAGRANTFILE env var to specify alternate filename for Vfile
Test to make sure hooks return the action runner result