Explictly cast division to float.

- If you include mathn, a Rational is returned from #/, so we need
to explictly cast to a float.
Test Honeybadger::Stats.memory
Test Honeybadger::Stats.load
Be more lenient when describing keys.

1.8.7 doesn't guarantee the order of hash keys.
Release 1.10.2
Merge tag 'v1.10.2' of github.com:honeybadger-io/honeybadger-ruby