Added endpoint for creating relations
Added endpoint for deleting relationships
Added authorization to creating and deleting relations
Add create and delete relation links to representers.
Use old prototype autocomplete in relations tab.
WIP Refactoring relations directives to correspond to relations not work packages.

This seems like an awfully long way round now to achieve having the activity object and thus its delete link available in the directive. Have also broken parent and child relations since they are not actually relations.
WIP sketchily wired up create/delete relations. No tests or validation handling.
Add separate directive for child work packages even though it looks awfully similar to relations.
Wire back up read only children/parent and add child button linking to old create view.
Some basic validation error handling in angular for api requests.
WIP trying to fix all the karma tests. not going too well.
Having a break from trying to test relations directive as i'm demoralised.
Using a $timeout approach to test relations directive.
Add permissions for add/remove relations.
Did sneaky css tricks to get the relations autocomplete looking okish.
Merge branch 'dev' into feature/frontend-create-and-delete-relationship

Conflicts:
	lib/api/v3/work_packages/work_package_representer.rb
	spec/lib/api/v3/work_packages/work_package_representer_spec.rb
Put back in missing dev after merge cockup.
Clean up the pr a bit.
Track down super irritating related to/by bug
Rename relations api namespace from id to relation_id.