Remove registration of BP template stack

[r-a-y]

Hi Marshall,

Is there a reason why /cbox-theme/templates/plugins/buddypress is a separate folder and not moved straight to /cbox-theme/buddypress? Is this just for file organization?

If there isn't a reason, we can drop the call to register the template stack in /engine/plugins/buddypress/base.php and move the directory to the cbox-theme/buddypress to avoid some file_exists() checks.

[MrMaz]

Infinity core is going to support a ton of plugins so I'm trying to keep the root dir as clean as possible. If there is an issue with the stack, I am willing to rethink it.