updates to Vagrantfile

* set cluster name to vagrant
* set variable single_node_cluster to signal that replication should be
set to 1 on all volumes
* add shell command in install_cluster to set replication to 1
* moved host only network to 192.168.99 to avoid a conflict on my
laptop. hopefully does not cause anyone else problems.
* removed firewall port stuff from zookeeper install. Assume we're
uninstalling the firewall. Anyways, firewall management should probably
go elsewhere.
Merge pull request #15 from vicenteg/vagrant-update

updates to Vagrantfile