Allow hashie to go up to 3.x

all tests pass, cross yer fingers matey

Author: David Haley

restforce.gemspec

@@ -18,7 +18,7 @@ Gem::Specification.new do |gem|
   gem.add_dependency 'faraday', '~> 0.9.0'
   gem.add_dependency 'faraday_middleware', '>= 0.8.8'
   gem.add_dependency 'json', ['>= 1.7.5', '< 1.9.0']
-  gem.add_dependency 'hashie', ['>= 1.2.0', '< 2.1']
+  gem.add_dependency 'hashie', ['>= 1.2.0', '< 4']
 
   gem.add_development_dependency 'rspec', '~> 2.14.0'
   gem.add_development_dependency 'webmock', '~> 1.13.0'