Fix Rack spec URL
Restore missing compilation durations
Remove unused @stop_times
Merge pull request #379 from nanoc/bug/missing-compilation-durations

Restore missing compilation durations
Improve internal/external link check summary
Merge pull request #392 from nanoc/feature/better-link-check-summary

Improve internal/external link check summary
Let bundler decide development dependencies
Include yardoc/handlers in gem
Make less test less strict
Do not use Rubocop from git
Add MRI 2.1.0 to Travis config
Warn when multiple preprocessors are defined
Add preliminary release notes for 3.6.8
Handle stylesheets more generically in default site
Do not show multiple preprocessor warning for first definition
Merge pull request #395 from nanoc/enhancement/default-rules-handling-stylesheets

Handle stylesheets more generically in default site
Merge pull request #396 from nanoc/bug/double-preprocessor-warning

Do not show multiple preprocessor warning for first definition
Add release note for new default stylesheet handling
Add missing issue numbers to release notes
Do not uninstall ffi before running tests anymore