Revert "Better jquery-rails version constrants, thanks to @jarinudom"

This reverts commit fffdcfb.
Fixes activeadmin#54

Author: elia

activeadmin-mongoid.gemspec

@@ -20,8 +20,7 @@ Gem::Specification.new do |gem|
 
   gem.add_runtime_dependency 'mongoid',     ['> 3.0', '< 5.0']
   gem.add_runtime_dependency 'activeadmin', '~> 0.6'
-  gem.add_runtime_dependency 'jquery-rails',    '>= 3.0.0'
-  gem.add_runtime_dependency 'jquery-ui-rails', '>= 4.0.0'
+  gem.add_runtime_dependency 'jquery-rails', '< 3.0' # in which they remove jquery-ui
   gem.add_runtime_dependency 'sass-rails',  ['>= 3.1.4', '< 5.0']
 
   gem.add_development_dependency 'rspec-rails',  '~> 2.7'