Add ability to inherit custom fields from RailsAdmin::Config::Fields::Association

field.properties instance variable is lost when you configure new custom field
Add has_description module in order to show description messages
Add description to index action.
Update rails_admin.scss.erb
Fix rubocop offenses
Fix Twitter Bootstrap reference URLs
Help block is showing for hidden field
Keep up to kaminari 0.16.0
Upgrade to RSpec 3
Fix RuboCop offenses
Merge pull request #1973 from rafaellima/add-description

Add description
Merge pull request #1976 from rickr/issue_1956

Update rails_admin.scss.erb
Merge pull request #1997 from nfedyashev/fix_twitter_bootstrap_urls

Fix Twitter Bootstrap reference URLs
Fix RuboCop offense
Revert "Keep up to kaminari 0.16.0"

This reverts commit 99628188362cf7d46a25e7d1424a2c8910a0b62a.
Looks like these changes were unintentional in kaminari 0.16.0.
Merge remote-tracking branch 'upstream/pr/1726'

Conflicts:
	lib/rails_admin/config/has_fields.rb
Spec for #1726
Mongoid build was failing
Nope

https://twitter.com/ashedryden/status/479746771325693952
Spec for #2003