Code review comment for lp:~adeuring/launchpad/bug-446600

This branch fixes bug 446600: "HWSubmissionMissingFields exceptions should be updated to be informational only"

The fix is quite simple: Diogo added in r9660 a method handling() to our ErrorReportingUtility, which allow to label logged OOPSes as being informational. So I changed the call error_utility.raising() to error_utlitiy.handling()

Test: ./bin/test -f canonical pagetests.hwdb

Launchpad lint =

Checking for conflicts. and issues in doctests and templates.
Running jslint, xmllint, pyflakes, and pylint.
Using normal rules.

Linting changed files:
  lib/canonical/launchpad/browser/hwdb.py
  lib/canonical/launchpad/pagetests/hwdb/01-submit-data.txt