[CentOS-devel] We need a newer Vagrant in SCL

Hello,

Our cico test for testing our Vagrant images have support for optionally 
using vagrant-vbguest.  This is now failing with:


+ scl enable sclo-vagrant1 'vagrant plugin install vagrant-vbguest'
Installing the 'vagrant-vbguest' plugin. This can take a few minutes...
Bundler, the underlying system Vagrant uses to install plugins,
reported an error. The error is shown below. These errors are usually
caused by misconfigured plugin installations or transient network
issues. The error from Bundler is:

Authentication is required for http://gems.hashicorp.com/.
Please supply credentials for this source. You can do this by running:
  bundle config http://gems.hashicorp.com/ username:password
Build step 'Execute shell' marked build as failure


I think this is caused by the older version we have in SCL - I can 
install vagrant-vbguest without any issues on Vagrant 1.9.3 (on OS X). 
I now reverted the test to not use vagrant-vbguest, but it's still 
failing because SCL Vagrant doesn't support VirtualBox 5.1.x.  Oracle 
already put a warning on the download page for VirtualBox 5.0.x: 
"VirtualBox 5.0.x runs out of support, switch to VirtualBox 5.1.x!"

https://www.virtualbox.org/wiki/Download_Old_Builds_5_0


We risk becoming unable to automatically test our images with VirtualBox 
- could we get a Vagrant update in SCL, please?

Thanks,
Laurentiu