Fix typo for Peugeot

Glad we didn't pick Citroën or Škoda.
Revise Changelog entry
Differentiate remote from local coverage

Invoke tests with COVERALLS=true or COVERAGE=true to produce remote or local
coverage reports, respectively.
Drop tests calling #set_slug

We shouldn't test private methods unless required. Then, these tests are
outdated and not adding coverage.
Fix whitespace in tests
Merge pull request #569 from xymbol/minor-changes

Minor changes
Merge pull request #568 from xymbol/fix-tests

Fix tests