Updates capybara to 2.4.4

Updates capybara to 2.4.4 from 2.4.1
Update webmock to 1.20.4
Updates yard to 0.8.7.6
Update chunky_png to 1.3.3

chunky_png is used by compass-rails.
Merge pull request #690 from codeforamerica/upgrade-capybara

Updates capybara to 2.4.4
Merge pull request #698 from codeforamerica/upgrade-chunky_png

Update chunky_png to 1.3.3
Merge pull request #697 from codeforamerica/upgrade-yard

Updates yard to 0.8.7.6
Merge pull request #696 from codeforamerica/upgrade-webmock

Update webmock to 1.20.4
Updates coveralls to 0.7.1