Corrects error during run of grpc-demo

ruby/Gemfile

@@ -3,13 +3,4 @@
 
 source 'https://rubygems.org/'
 
-# Update this to reflect the local installation of gRPC.
-gem 'grpc', path: '~/grpc/src/ruby'
-
-# TODO: fix this if/when the gRPC repo structure changes.
-#
-# At the moment it's not possible to use grpc Ruby via git/github reference
-#
-# git 'git@github.com:grpc/grpc.git' do
-#   gem 'grpc'
-# end
+gemspec

ruby/grpc-demo.gemspec

@@ -17,7 +17,7 @@ Gem::Specification.new do |s|
   s.require_paths = ['lib']
   s.platform      = Gem::Platform::RUBY
 
-  s.add_dependency 'grpc', '~> 0.5.0'
+  s.add_dependency 'grpc', '~> 0.6.0'
 
   s.add_development_dependency 'bundler', '~> 1.7'
 end