Tweak gem dependencies

`omniauth-oauth2` depends on `omniauth` so no need to depend on both.

Author: pjg

omniauth-linkedin-oauth2.gemspec

@@ -18,12 +18,11 @@ Gem::Specification.new do |gem|
   gem.test_files    = gem.files.grep(%r{^(test|spec|features)/})
   gem.require_paths = ["lib"]
 
-  gem.add_runtime_dependency 'omniauth', '~> 1.0'
   gem.add_runtime_dependency 'omniauth-oauth2'
 
-  gem.add_development_dependency 'bundler', '~> 1.3'
+  gem.add_development_dependency 'bundler'
   gem.add_development_dependency 'rake'
 
-  gem.add_development_dependency 'rspec', '~> 3.0'
+  gem.add_development_dependency 'rspec'
   gem.add_development_dependency 'simplecov'
 end