CI: retry failed tests

It's an unfortunate reality that PhantomJS does crash from time to time,
and when you have over 500 tests running on 6 different rubies there is
a high chance that at least on of those runs will fail. So hopefully
this will help mitigate that.

.gitignore

@@ -2,3 +2,4 @@
 /spec/support/custom_phantomjs_called
 /ci/Gemfile.*.lock
 /spec/tmp
+/rspec.failures

.rspec

@@ -0,0 +1 @@
+--format progress

.travis.yml

@@ -5,6 +5,7 @@ before_script:
   - sudo ci/install_phantomjs
   - "export PATH=phantomjs/bin:$PATH"
   - phantomjs --version
+script: rake ci
 rvm:
   - 1.9.3
   - 1.9.2

Rakefile

@@ -4,6 +4,7 @@ require 'rspec/core/rake_task'
 base = File.dirname(__FILE__)
 require base + "/lib/capybara/poltergeist/version"
 require 'coffee-script'
+require 'rspec-rerun'
 
 task :autocompile do
   system "guard"
@@ -22,6 +23,7 @@ end
 RSpec::Core::RakeTask.new('test')
 
 task :default => [:compile, :test]
+task :ci => 'rspec-rerun:spec'
 
 task :release do
   puts "Releasing #{Capybara::Poltergeist::VERSION}, y/n?"

poltergeist.gemspec

@@ -26,6 +26,7 @@ Gem::Specification.new do |s|
   s.add_development_dependency 'image_size',         '~> 1.0'
   s.add_development_dependency 'coffee-script',      '~> 2.2.0'
   s.add_development_dependency 'guard-coffeescript', '~> 1.0.0'
+  s.add_development_dependency 'rspec-rerun',        '~> 0.1'
 
   s.files        = Dir.glob("{lib}/**/*") + %w(LICENSE README.md)
   s.require_path = 'lib'