Revert "added omniauth to identity.rb"

This reverts commit e4d13e4729c757490d9f47ab93e2771d3f503f87.
Revert "added omniauth provider to devise.rb"

This reverts commit 9b0a113fc8f77a5ee3a7a8b8d291bb83ce43b027.
Revert "added omniauth_callbacks_controller.rb"

This reverts commit cf86379985da5456108431319609e9e58d8653dc.