parsemail: Mail error information to ADMINS when parsing fails

parsemail: Mail error information to ADMINS when parsing fails

We can use the built-in mechanism from django to send error emails when
failing to parse a mail. The error mails will have contain the full
guitly mail and the corresponding backtrace for debugging purposes.

v2: Add 2 PEP8 blank lines (Stephen Finucane)
v3: Remove one blank line (Stephen Finucane)

Signed-off-by: Damien Lespiau <damien.lespiau@intel.com>
Acked-by: Stephen Finucane <stephen.finucane@intel.com>