simple refactoring for the reports: maybe this gets it below D
major refactoring of reports into separare classes

reports now live in separate classes: This brought up several issues
with buggy templates; lots of duplicate code has now been removed.

Still needs some view-testing, and maybe some unit-testing for the
service.
Worked in the review-remarks, added proper coypright notices where missing
abstract-class is ActiveRecord only, removing it.
added changelog-entry
limits principals returned by the autocompleter to only active or registerd
cleaning up unused code, rewriting scopes
updates changelog
adds a user pagination controller for timelines
removes scopes also present on the superclass
handles principals pagination controller same as users
moves pagination to api::v2
streamlines pagination specs, enables using index action
added the status to the planning-elements-api
fixed a typo
Merge pull request #514 from opf/fix/add_status_to_pe_api

added the status to the planning-elements-api
prevents timelines spec to change settings for following specs
moves remaining paginations under api/v2/pagination scope
removes outdated routes
shortens ApplicationController spec