[Acceptance testing] Vagrant snapshot/restore networking issues with some host machines

During the development of our internal QA acceptance test framework that runs on vagrant/virtualbox VM's we encountered the need of using the snapshot/restore in vagrant so we could handle situations where the logstash installation state should be reverted to a known state.

The issue detected is basically that after a bootstrap/restore dance is performance the target host of this restore is not accessible from the host machine through ssh, might https://github.com/mitchellh/vagrant/issues/391 be related.

In a test machine, similar to our CI environment, that ubuntu (14.04) as host, is it possible to reproduce this error with this small steps:
- vagrant up _vm-name_
- vagrant snapshot push _vm-name_
- vagrant snapshot pop _vm-name_

the target OS for this test has been ubuntu versions from 14.04 to 16.04 and this is a common output for it https://gist.github.com/purbon/aaf983e5f5c0d4014a94cfc7fb08c7e9

if before the snapshot is requested we halt the machine using `vagrant halt vm-name` the snapshot/restore dance is done without any issue.

Also important to notice that doing the steps commented earlier with a debian-8 target OS we're not seeing this issue with snapshot (see https://gist.github.com/purbon/3852d18af6e76b8ff569ab47cf045ac2 for details)

During development, this issue was triggered for one developer having this specifications:

```
Vagrant 1.8.1
MacOS X 10.11.3
Target OS was ubuntu: 1504.
jruby 1.7.23 (1.9.3p551) 2015-11-24 f496dd5 on Java HotSpot(TM) 64-Bit Server VM 1.8.0_20-b26 +jit [darwin-x86_64]
```

but not for other developer having:

```
Vagrant 1.8.1
MacOS X 10.10.5
virtualbox 5.0.2
jruby 1.7.20 (1.9.3p551) 2015-05-04 3086e6a on Java HotSpot(TM) 64-Bit Server VM 1.8.0_40-ea-b15 +jit [darwin-x86_64]
```

the test machine specs are:

```
Ubuntu 14.04.4 LTS, Trusty Tahr
virtualbox-5.0 5.0.20-10693`
Vagrant 1.8.1
```

as of now, is prefered you avoid using snapshot / restore in your acceptance test code, or in case you need you should make sure either to:
- halt the machine before you run the snapshot.
- be sure the process will run smooth for your target os.

related to #5324