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
Merge pull request #12725 from terminalmage/issue12696-2014.1

Jinja renderer, timezone module/state fixes (2014.1 branch)