fix travis

vagrant-azure.gemspec

@@ -26,7 +26,6 @@ Gem::Specification.new do |s|
   s.add_runtime_dependency 'haikunator',            '~>1.1'
   s.add_runtime_dependency 'highline',              '~>1.7'
 
-  s.add_development_dependency 'bundler',           '~>1.10.5'
   s.add_development_dependency 'rake',              '~>11.1'
   s.add_development_dependency 'rspec',             '~>3.4'
   s.add_development_dependency 'simplecov',         '~>0.11'