Looking up a proposal and getting all its elements like that won't work in the case when only a template exists - that one will have self.barclamp returning `template` and this particular method fails:

```ruby
>> x = ProposalObject.find_barclamp('keystone')
>> x.barclamp
     => "template"
>> x.all_elements
NoMethodError: undefined method `[]' for nil:NilClass
     from /opt/dell/crowbar_framework/app/models/proposal_object.rb:198:in `all_elements'
     from (irb):3
```
Should I extend this method to accept a bc_name parameter, defaulting to ```self.barclamp``` and call it from the ServiceObject, or can you think of a better approach?