https://bugs.webkit.org/show_bug.cgi?id=70119

Reviewed by Adam Barth.

* Scripts/webkitpy/style/checker.py: Added ChangeLogChecker categories to the big list.
* Scripts/webkitpy/style/checkers/changelog.py: Declared categories, used in ChangeLogChecker.
* Scripts/webkitpy/tool/commands/download.py: Made LandCowboy use filter.
* Scripts/webkitpy/tool/commands/download_unittest.py: Tweaked the test.
* Scripts/webkitpy/tool/commands/upload_unittest.py: Ditto.
* Scripts/webkitpy/tool/steps/checkstyle.py: Made check_style_filter work.
* Scripts/webkitpy/tool/steps/options.py: Added new option, check-style-filter.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@97504 268f45cc-cd09-0410-ab3c-d52691b4dbfc