Add selenium-webdriver as development dependency

Capybara 2.1 will make selenium-webdriver optional.

Gemfile.lock

@@ -74,4 +74,5 @@ DEPENDENCIES
   mini_magick
   rake
   rspec (~> 2.6.0)
+  selenium-webdriver
   sinatra

capybara-webkit.gemspec

@@ -27,5 +27,6 @@ Gem::Specification.new do |s|
   s.add_development_dependency("mini_magick")
   s.add_development_dependency("rake")
   s.add_development_dependency("appraisal", "~> 0.4.0")
+  s.add_development_dependency("selenium-webdriver")
 end
 

gemfiles/2.0.gemfile.lock

@@ -68,4 +68,5 @@ DEPENDENCIES
   mini_magick
   rake
   rspec (~> 2.6.0)
+  selenium-webdriver
   sinatra

gemfiles/2.1.gemfile.lock

@@ -25,11 +25,15 @@ GEM
     appraisal (0.4.1)
       bundler
       rake
+    childprocess (0.3.8)
+      ffi (~> 1.0, >= 1.0.11)
     diff-lcs (1.1.3)
+    ffi (1.4.0)
     json (1.7.7)
     mime-types (1.21)
     mini_magick (3.5.0)
       subexec (~> 0.2.1)
+    multi_json (1.6.1)
     nokogiri (1.5.6)
     rack (1.5.2)
     rack-protection (1.3.2)
@@ -45,12 +49,19 @@ GEM
     rspec-expectations (2.6.0)
       diff-lcs (~> 1.1.2)
     rspec-mocks (2.6.0)
+    rubyzip (0.9.9)
+    selenium-webdriver (2.30.0)
+      childprocess (>= 0.2.5)
+      multi_json (~> 1.0)
+      rubyzip
+      websocket (~> 1.0.4)
     sinatra (1.3.5)
       rack (~> 1.4)
       rack-protection (~> 1.3)
       tilt (~> 1.3, >= 1.3.3)
     subexec (0.2.2)
     tilt (1.3.3)
+    websocket (1.0.7)
 
 PLATFORMS
   ruby
@@ -62,4 +73,5 @@ DEPENDENCIES
   mini_magick
   rake
   rspec (~> 2.6.0)
+  selenium-webdriver
   sinatra