feat(tree list): nested tree list form
VIP - will be rebased

needs to be fixed implementation (one falling test)
feat(filter): added predicate one_of to the filter
chore: removed unused paperclip gem from Gemfile
fix: change arel predicate in ransack one_of predicate
Merge pull request #8 from zorec/master

test: add tests for new, create, edit, update and filter.
fix: i18n set enforce_available_locales and removed comments and focus on test
feat: xml import
fix: fix broken spec for optional field
fix: removed duplicated gems - there are already in basepack.gemspec
test: WIP - import specs
chore: added sqlite to Gemfile because of TravisCI
fix: set properly enum_options for fields in associated model in Query Form
fix: fix typo of ActsAsTaggableOn::Tagging in rails_admin included models
feat: add one_of opertor to query language
fix(bulk_edit): boolean type shoud be check/uncheck or let it as is
fix(tree): fix tests
Merge branch 'tree'

Conflicts:
	Gemfile
	spec/dummy_app/app/assets/stylesheets/application.css
	spec/dummy_app/app/models/project.rb
	spec/dummy_app/db/schema.rb
	spec/spec_helper.rb