updating default.yml to not break ubuntu, specifically removing mac only...

... recipes from global, the rbenv attr fail to pick up current user and the rebenv recipe was updated with new recipe for debian

This requires the changes in the kono_workstation rbenv. 

Removing: 
 Flash - Recipe is mac only there are some workarounds, but I think it's in Chrome
 Core_Gems - not necessary use the rbenv attributes in the recipe
Rbenv attribute for current user does not correctly handle the parameter instead it literally looks for "current_user" as the user.  See rbenv recipe change in kono_workstation.