Curtin Userdata customization: add multipath support

#Add multipath support installing multipath-tools and multipath.conf in /etc

diff -c curtin_userdata_ubuntu_amd64_generic_xenial_with-csduser curtin_userdata_ubuntu_amd64_generic_xenial_with-csduser-and-multipath
*** curtin_userdata_ubuntu_amd64_generic_xenial_with-csduser	Wed Mar  8 09:16:58 2017
--- curtin_userdata_ubuntu_amd64_generic_xenial_with-csduser-and-multipath	Wed Mar  8 09:15:38 2017
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*** 39,44 ****
--- 39,47 ----
    package_02_update_install: ["curtin", "in-target", "--", "sh", "-c", "apt-get update --quiet && apt-get --assume-yes install aptitude"]
    emacs_update_install: ["curtin", "in-target", "--", "sh", "-c", "apt-get update --quiet && apt-get --assume-yes install emacs"]
   
+   multipath_01_install: ["curtin", "in-target", "--", "apt-get", "-y", "install", "multipath-tools"]
+   multipath_02_conf: ["curtin", "in-target", "--", "sh", "-c", "/bin/echo 'defaults {@ #find_multipaths yes@ verbosity 2@ path_grouping_policy multibus@ polling_interval 5@ max_polling_interval 20@ max_fds \"max\"@ queue_without_daemon \"no\"@ flush_on_last_del \"no\"@ user_friendly_names \"yes\"@ fast_io_fail_tmo 5@ log_checker_err always@ retain_attached_hw_handler no@ detect_prio no@}@blacklist {@ devnode \"^(ram|raw|loop|fd|md|dm-|sr|scd|st)[0-9]*\"@ devnode \"^drbd*\"@ devnode \"^hd[a-z]\"@ devnode \"^(td|hd)[a-z]\"@ devnode \"^dcssblk[0-9]*\"@ devnode \"^cciss!c[0-9]d[0-9]*\"@ #/dev/sda@ wwid 36b083fe0c812d5001bd94f7318561ba3@}@devices {@ device {@ vendor \"DELL\"@ product \"MD38xxf\"@ path_grouping_policy group_by_prio@ prio rdac@ path_checker rdac@ path_selector \"round-robin 0\"@ hardware_handler \"1 rdac\"@ failback immediate@ features \"2 pg_init_retries 50\"@ no_path_retry 30@ rr_min_io 100@ }@}@multipaths {@}' >> /etc/multipath.conf"]
+   multipath_03_confupdate: ["curtin", "in-target", "--", "sh", "-c", "/bin/sed -ie \"s/@/\\n/g\" /etc/multipath.conf"]
  
  power_state:
    mode: reboot