Curtin Userdata customization: timezone, security/limits

# Set timezone and reconfigure tzdata
# Add couple of lines to /etc/security/limits.conf (Sysctl parameters are handled via Juju)
# Add pre-up condition for eth0: if declared in a bond, then do not activate as single interface

diff -c curtin_userdata_ubuntu_amd64_generic_trusty.orig curtin_userdata_ubuntu_amd64_generic_trusty_csd 

*** curtin_userdata_ubuntu_amd64_generic_trusty.orig    2016-09-22 10:05:35.604408950 +0200
--- curtin_userdata_ubuntu_amd64_generic_trusty_csd     2016-09-22 11:08:45.042776292 +0200
***************
*** 24,29 ****
--- 24,33 ----
    driver_06_depmod: ["curtin", "in-target", "--", "depmod"]
    driver_07_update_initramfs: ["curtin", "in-target", "--", "update-initramfs", "-u"]
  {{endif}}
+   timezone_01_config: ["curtin", "in-target", "--", "sh", "-c", "ln -sf /usr/share/zoneinfo/Europe/Vatican /etc/timezone"]
+   timezone_02_set: ["curtin", "in-target", "--", "sh", "-c", "dpkg-reconfigure --frontend noninteractive tzdata"]
+   limits_01_add: ["curtin", "in-target", "--", "sh", "-c", "/bin/echo '*  soft  nofile  1048576' >> /etc/security/limits.conf ; /bin/echo '*  hard  nofile  1048576' >> /etc/security/limits.conf"]

  power_state:
    mode: reboot