Admin accounts controller cleanup (#1664)

* Remove unused account_params method in admin/accounts controller

* Introduce AccountFilter to find accounts

* Use AccountFilter in admin/accounts controller

* Use more restful routes admin silence and suspension area

* Add admin/silences and admin/suspensions controllers

spec/models/account_filter_spec.rb

@@ -0,0 +1,31 @@
+require 'rails_helper'
+
+describe AccountFilter do
+  describe 'with empty params' do
+    it 'defaults to alphabetic account list' do
+      filter = AccountFilter.new({})
+
+      expect(filter.results).to eq Account.alphabetic
+    end
+  end
+
+  describe 'with invalid params' do
+    it 'raises with key error' do
+      filter = AccountFilter.new(wrong: true)
+
+      expect { filter.results }.to raise_error(/wrong/)
+    end
+  end
+
+  describe 'with valid params' do
+    it 'combines filters on Account' do
+      filter = AccountFilter.new(by_domain: 'test.com', silenced: true)
+
+      allow(Account).to receive(:where).and_return(Account.none)
+      allow(Account).to receive(:silenced).and_return(Account.none)
+      filter.results
+      expect(Account).to have_received(:where).with(domain: 'test.com')
+      expect(Account).to have_received(:silenced)
+    end
+  end
+end