Updates gem dependencies, style rules
diff --git a/src/ruby/grpc.gemspec b/src/ruby/grpc.gemspec
index a50d035..12d4ab1 100755
--- a/src/ruby/grpc.gemspec
+++ b/src/ruby/grpc.gemspec
@@ -22,16 +22,16 @@
   s.platform      = Gem::Platform::RUBY
 
   s.add_dependency 'google-protobuf', '~> 3.0.0alpha.1.1'
-  s.add_dependency 'googleauth', '~> 0.4'
+  s.add_dependency 'googleauth', '~> 0.4'  # reqd for interop tests
   s.add_dependency 'logging', '~> 1.8'
   s.add_dependency 'minitest', '~> 5.4'  # reqd for interop tests
   s.add_dependency 'xray', '~> 1.1'
 
-  s.add_development_dependency 'bundler', '~> 1.7'
-  s.add_development_dependency 'rake', '~> 10.0'
-  s.add_development_dependency 'rake-compiler', '~> 0'
-  s.add_development_dependency 'rubocop', '~> 0.28.0'
-  s.add_development_dependency 'rspec', '~> 3.0'
+  s.add_development_dependency 'bundler', '~> 1.9'
+  s.add_development_dependency 'rake', '~> 10.4'
+  s.add_development_dependency 'rake-compiler', '~> 0.9'
+  s.add_development_dependency 'rubocop', '~> 0.30'
+  s.add_development_dependency 'rspec', '~> 3.2'
 
   s.extensions = %w(ext/grpc/extconf.rb)
 end