protect Enumeration with ActiveModel::ForbiddenAttributesProtection
update changelog
feed permitted params to mass assignments in enumerations_controller
Merge branch 'dev' into fix/ma_enum_controller

Conflicts:
	app/models/permitted_params.rb
	doc/CHANGELOG.md
fix unfortunate typos + review feedback
remove attr_protected from Enumeration
Merge branch 'dev' into fix/ma_enum_controller

Conflicts:
	doc/CHANGELOG.md
introduce render_400 (bad request) method in application controller
it should not be possible anymore to update/create enumerations so that they have a non existent type
Merge pull request #734 from opf/fix/ma_enum_controller

Fix/ma enum controller
new version; updated changelog
tells travis to use 2.0
updates changelog
fixed small layout bug

of project navigation toggler
- added transition for project navigation folding
Fixes migration for empty string default values.

Both NULL and empty string should be disregarded here. &:default_value
did not account for that.
Merge pull request #751 from opf/feature/ruby_2_0_minimal

tells travis to use 2.0