Fix README how to set global config overrides
The first parameter of `Plugin.action_hook` is our hook name

The value is currently not even used. The second parameter specifies the
machine action name where to hook to, and it defaults to `ALL_ACTIONS`.
Hook after `WaitForCommunicator` action if it exists

Vagrant 1.3.0 introduced[1] new WaitForCommunicator action that ensures
the VM is booted and ready for SSH connections. So hook after it if it
exists. The default still stays to hook after the `Boot` action.

[1]: https://github.com/mitchellh/vagrant/commit/261d0ef
Add rake to development dependencies
reorder gem dependencies

group into "our" dependencies and those we use, but are provided by vagrant.
Drop version pin on gems provided by vagrant.
prepare dev version
Hook after VirtualBox action instead of Builtin generic
Cope with UbuntuCloudImage by default

On Ubuntu, always try to remove conflicting installations of GuestAdditions by removing vm packages: virtualbox-guest-dkms virtualbox-guest-utils virtualbox-guest-x11
Update Changelog with 0.10.0 dev changes
prepare preview of 0.10.0 release for early birds

and those waiting desperately for bug fixes