[FIX] product: name_get of product.attribute.value

name was confusing for bom and product if the value of the attribute is display without the attribute name
added key in context to keep the previous behaviour (e.g. in product view where the attribute name is present)
[FIX] mrp: The attribute on bom lines is not filtered in function of the selected product template
[FIX] mail: _fields['type'].selection is a callable

This revert partially the rev. f2e4a10e1a58c932f9a989e642771f5ae75d756a

  File "/home/odoo/src/odoo/8.0/addons/mail/mail_mail.py", line 76, in default_get
      if context and context.get('default_type') and context.get('default_type') not in self._fields['type'].selection:
      TypeError: argument of type 'function' is not iterable