Make `vagrant provision` multiple times not throw errors

[wjhdev]

Re-provisioning currently throws (mostly) benign errors. Improve provisioning to avoid this.

==> default: Notice: /Stage[main]/Main/Exec[apt_update]/returns: W: Some index files failed to download. They have been ignored, or old ones used instead.
==> default: Error: apt-get update returned 100 instead of one of [0]
==> default: Error: /Stage[main]/Main/Exec[apt_update]/returns: change from notrun to 0 failed: apt-get update returned 100 instead of one of [0]

resulting in:

The SSH command responded with a non-zero exit status. Vagrant
assumes that this means the command failed. The output for this command
should be in the log above. Please read the output to determine what
went wrong.