Relax Bundler dependency

This were causing the build to not able to run, because Bundler is now
at 1.7.x.

Author: Prem Sichanugrist

codeclimate-services.gemspec

@@ -22,6 +22,6 @@ Gem::Specification.new do |spec|
   spec.add_dependency "virtus", "1.0.0"
   spec.add_dependency "nokogiri", "~> 1.6.0"
   spec.add_dependency "activemodel", "~> 3.0"
-  spec.add_development_dependency "bundler", "~> 1.6.2"
+  spec.add_development_dependency "bundler", ">= 1.6.2"
   spec.add_development_dependency "rake"
 end