Reduce run time of travis build's html check step

We don't need to check all links on the internal listing pages.
Also switched to debug output for some more progress reporting.

Author: foosel

.travis.yml

@@ -4,10 +4,10 @@ rvm:
 
 script:
 - bundle exec jekyll build
-- bundle exec htmlproofer ./_site --only-4xx --check-favicon --check-html --file-ignore "/\.\/_site\/search\/index\.html/"
 - bundle exec jsonlint ./_site/plugins.json
 - bundle exec jsonlint ./_site/search.json
 - bundle exec jsonlint ./_site/notices.json
+- bundle exec htmlproofer ./_site --only-4xx --check-favicon --check-html --file-ignore "/\.\/_site\/search\/index\.html/","/\.\/_site\/by_(author|tag|date|name)\/index\.html/" --log-level ':debug'
 
 branches:
   only: