Update excon development/test dependency to version ~> 0.6

Gemfile

@@ -5,14 +5,14 @@ source "http://rubygems.org"
 # and rake tasks are available in development mode:
 group :development, :test do
   gem 'patron', '~> 0.4', :platforms => :ruby
-  gem 'sinatra', '~> 1.1'
+  gem 'sinatra', '~> 1.2'
   gem 'typhoeus', '~> 0.2', :platforms => :ruby
-  gem 'excon', '~> 0.5.8'
+  gem 'excon', '~> 0.6'
   gem 'em-http-request', '~> 0.3', :require => 'em-http', :platforms => :ruby
   gem 'em-synchrony', '~> 0.2', :require => ['em-synchrony', 'em-synchrony/em-http'], :platforms => :ruby_19
   gem 'webmock'
   # ActiveSupport::JSON will be used in ruby 1.8 and Yajl in 1.9; this is to test against both adapters
-  gem 'activesupport', '~> 2.3.8', :require => nil, :platforms => [:ruby_18, :jruby]
+  gem 'activesupport', '~> 2.3', :require => nil, :platforms => [:ruby_18, :jruby]
   gem 'yajl-ruby', :require => 'yajl', :platforms => :ruby_19
 end