Add option to make sshfs default mount option

[varac]

From the README I know how to use sshfs for a particular mountpoint, but when working with provisioning vagrant still defaults to nfs for the dynamically generated mountpoints.
How do I tell Vagrant to always use sshfs instead of nfs for all mountpoints ?

A VAGRANT_SSHFS_ALWAYS=true env variable would be great, but I'm fine with any way to accomplish this.

[varac]

Here's an example of three mountpoints of a box that uses puppet provisioning and uses random mountpoints which I cannot get mounted with sshfs:

:/home/varac/... on /vagrant type fuse.sshfs (rw,nosuid,nodev,relatime,user_id=0,group_id=0,allow_other)

192.168.121.1:/home/varac/.../provisioning/manifests on /tmp/vagrant-puppet/manifests-2797ed1130cdd22886ca4e0f5dcf8c87 type nfs (rw,relatime,vers=3,rsize=32768,wsize=32768,namlen=255,hard,proto=udp,timeo=11,retrans=3,sec=sys,mountaddr=192.168.121.1,mountvers=3,mountport=45094,mountproto=udp,local_lock=none,addr=192.168.121.1)
192.168.121.1:/home/varac/.../provisioning/modules on /tmp/vagrant-puppet/modules-f20d1267d99a620662dec6fbf8fd9639 type nfs (rw,relatime,vers=3,rsize=32768,wsize=32768,namlen=255,hard,proto=udp,timeo=11,retrans=3,sec=sys,mountaddr=192.168.121.1,mountvers=3,mountport=45094,mountproto=udp,local_lock=none,addr=192.168.121.1)

[dustymabe]

You can do this by putting the following in your ~/vagrant.d/Vagrantfile file.

$ cat ~/vagrant.d/Vagrantfile 
Vagrant.configure(2) do |config|

    config.vm.allowed_synced_folder_types = [:sshfs, :rsync]
end

See this PR for more info: hashicorp/vagrant#5013

[dustymabe]

TODO: add docs for this and then close this issue