driver: Raise exception if option value is not available (#read_vm_option)
action/prepare_nfs_settings: Use Shared network instead of Host-Only for NFS exports

Completes task [GH-152]
Port changes from mitchellh/vagrant@7ccec33
Optimized error exceptions.
Use Shared IP from DHCP instead of detecting it via VM option.

VM options work only if Parallels Tools installed in the guest. So, we should to use universal
approach to support NFS in such guests as CoreOS, FreeBSD, OmniOS and so on.

Related to: [GH-152]
Fixed unit tests
Version bumped to 1.3.4
Release v.1.3.4

  Use Shared IP from DHCP instead of detecting it via VM option.
  Optimized error exceptions.
  Ported changes from mitchellh/vagrant@7ccec33
  action/prepare_nfs_settings: Use Shared network instead of Host-Only for NFS exports
  driver: Raise exception if option value is not available (#read_vm_option)