move session and signup related functions and constants to a module
use a scope instead of a subdomain for admins
send form url in case sign in fails
eliminate repeated code in sign in proccess
add password reseting methods
add admin password reseting views
add admin password reseting routes
renaming sign_in_tools to user_utils
fix redirection bug in session controller
Merge pull request #7 from psparabara/refactoring_admins

Refactoring admins