Fix centos/7 in Vagrant failing

[rdcuzins]

Provisioning failed when trying to apply kernel-devel package and mounting /vagrant would break

--- snip ---
No package kernel-devel-3.10.0-1127.el7.x86_64 available.
Error: Nothing to do
Unmounting Virtualbox Guest Additions ISO from: /mnt
umount: /mnt: not mounted
--- snip ---
Vagrant assumes that this means the command failed!

umount /mnt

Stdout from the command:

Stderr from the command:

umount: /mnt: not mounted

After the initial fail, have to run vagrant up keycloak once again which would cause the keycloak module to error due to /vagrant not being mounted.