Add explicit Ruby 1.9.3 dependency

Author: sferik

.travis.yml

@@ -1,6 +1,6 @@
 language: ruby
 rvm:
-  - 1.9
+  - 1.9.3
   - 2.0
   - 2.1
   - 2.2

geokit.gemspec

@@ -22,7 +22,7 @@ Gem::Specification.new do |spec|
   spec.test_files    = spec.files.grep(%r{^(test|spec|features)/})
   spec.require_paths = ["lib"]
 
-  spec.add_dependency "json", "~> 1.8"
+  spec.required_ruby_version = ">= 1.9.3"
   spec.add_development_dependency "bundler", "~> 1.0"
   spec.add_development_dependency "coveralls"
   spec.add_development_dependency "mocha"