handle case of failure during compile phase

Guard against attempting to emit metrics and events for attributes that
may not exist due to failures in early phases of a Chef run.

Fixes #51
trim updated resource list to 5 recent on failure

Place the 5 most recent updates resources above the stacktrace on
failure to help with inspection.

Also updates test cassettes with current test results.

Fixes #46
Release 0.5.0

See CHANGELOG.md for details.