Directs user to the app or Safari if no system account is present
Merge branch 'master' of https://github.com/akaralar/HIPSocialAuth
Fix Facebook Login Bug when no system account is present

When there is no system account found, the second login process starts
with Facebook again in the completion process but _authHandler
was being set to nil in the completion process so _authHandler
was not being called after the second login completed. Now
_authHandler is not being set to nil when the second login
starts so it is called at the end of the second login.