Admin reports controller improvements (#1714)

* Simplify admin/reports controller filtering for index

* Rename parameter to resolved

* Fix issue where reports view could not access filter_link_to

* Add coverage for admin/reports controller

* DRY up resolution of related reports for target account

* Clean up admin/reports routes

* Add Report#statuses method

* DRY up current account action taken params

* Rubocop styles

spec/fabricators/report_fabricator.rb

@@ -1,4 +1,6 @@
 Fabricator(:report) do
+  account
+  target_account { Fabricate(:account) }
   comment      "You nasty"
   action_taken false
 end