Fix timedatectl parsing for newer systemd releases

systemd 210 changed the output for timedatectl, changing 'Timezone' to
'Time zone'. This commit fixes a traceback that occurs in
timezone.get_zone for these newer versions of systemd.

Additionally, for get_zone() and get_hwclock(), parsing of timedatectl
has been changed from an ugly and unwieldy shell one-liner to actual
python logic.

Finally, output_loglevel has been set to 'debug' for all shell commands
in this module, part of a greater effort to make the logs less noisy.
Fix missing import
Merge pull request #12729 from terminalmage/fix-timedatectl-2014.1

Fix timedatectl parsing for newer systemd releases (2014.1 branch)
Improve jinja error reporting

Salt execution functions routinely raise SaltInvocationError and
CommandExecutionError exceptions. This commit catches them in the jinja
renderer and provides a nicely-formatted error message, preventing the
traceback from being in the render error that is printed to the CLI.
Raise exceptions when trying to read nonexistant files

Prevents a traceback when an invalid timezone is passed
Catch exceptions raised when comparing timezone
Fix lint failure