Fix #187 ability to read and append request headers
Allow JRuby to fail the CI for now

It's broken to to external issues, see bundler/bundler-api#36
Merge pull request #355 from route/187-set-headers

Fix #187 ability to read and append request headers
Merge pull request #353 from yaauie/fix-issue-349

Fix issue 349
Fix leak of phantomjs processes by adding a GC finalizer to the Capybara::Poltergeist::Client object that creates them (Fixes #348)