This is a follow up change of 63c1f784

- when upgradeSite is called, it will delete orphaned bt is we set
  delete_orphaned to true
- when there is provider calculation in the dependency list, look
  at both installed bt and to all the dependency tree

* fix the state of bt (new, old, present)
* make resolveBusinessTemplateListDependency returning all
  dependencies, even installed ones
* add upgradeSite method to install everything from top level bt
* the code to check version restriction has been removed but
  it should be  moved to another method

    - This permit we reuse it everywhere.

 - Arbitrary remove objects and delete workflow history is bad. This code
  was never used anyway.
 - Clean up code which is not used anywhere anymore, legacy from long ago
  implementation.

 - Create System Preference if do not exist
 - Handle BusinessTemplateUnknownError when portal_templates is unable to handle depedencies.

Thanks to this Computer Partitions can be in same category as Computers they
are contained in.

It will be used to represent various Computer models.

It will be used to create group of Computer.