Cleanup spec/support folder and spec/spec_helper

Changes:
* Move spec/monkeypatch to spec/support
* Remove unused support/shared_examples
* Move support/api to support/api_helpers to match module name
* Move support/login to support/login_helpers to match module name
* Move API specs to requests/api (convention over configuration)
* Remove unused support/js_patch
* Simplify login_as helper
* Move DatabaseCleaner stuff to its own support file
* Remove unnecessary configuration and requires from spec_helper

spec/support/db_cleaner.rb

@@ -0,0 +1,18 @@
+require 'database_cleaner'
+
+RSpec.configure do |config|
+  config.before do
+    if example.metadata[:js]
+      DatabaseCleaner.strategy = :truncation
+      Capybara::Selenium::Driver::DEFAULT_OPTIONS[:resynchronize] = true
+    else
+      DatabaseCleaner.strategy = :transaction
+    end
+
+    DatabaseCleaner.start
+  end
+
+  config.after do
+    DatabaseCleaner.clean
+  end
+end