Optimized n+1 queries in accounts Atom and HTML views

Added stack trace for SQL queries in development
Removed badly thought out accounts/lookup API

app/controllers/api/accounts/lookup_controller.rb

@@ -1,14 +0,0 @@
-class Api::Accounts::LookupController < ApiController
-  before_action :doorkeeper_authorize!
-  respond_to    :json
-
-  def index
-    @accounts = Account.where(domain: nil).where(username: lookup_params)
-  end
-
-  private
-
-  def lookup_params
-    (params[:usernames] || '').split(',').map(&:strip)
-  end
-end