Allow looking up users by an email address

Signed-off-by: Andrej Shadura <andrew.shadura@collabora.co.uk>

src/api/app/controllers/person_controller.rb

@@ -13,6 +13,8 @@ class PersonController < ApplicationController
   def show
     if params[:prefix]
         @list = User.where("login LIKE ?", params[:prefix] + '%')
+    elsif params[:email]
+        @list = User.where(:email => params[:email])
     else
         @list = User.all
     end