fix specs on travis

Author: manuelmeurer

rails_bootstrap_navbar.gemspec

@@ -21,7 +21,7 @@ Gem::Specification.new do |gem|
  gem.test_files = gem.files.grep(%r(^(test|spec|features)/))
  gem.require_paths = ['lib']
 
- gem.add_development_dependency 'rake'
+ gem.add_development_dependency 'rake', '< 11.0'
  gem.add_development_dependency 'rspec', '~> 2.13'
  gem.add_development_dependency 'guard-rspec', '~> 3.0'