Fix netapp_spec and pass a correct url

The netapp network device initialize method expects a NetApp filer and
no URL. This is now respected in the spec test.

Note: You might see some "Error : " messages messing the rspec output.
This is because the NetApp SDK likes to talk about the expected
exceptions.
Make it easier to execute NetApp API calls

The netapp provider now offers a method `netapp_commands` that works
similar to the `commands` provider method:

1) It makes it possible to define seperate methods for each api call you
   want to use
2) it will print a debug message for each api call
3) it raises an expection whenever the api call fails

Example: Inside your provider you can define a seperate method for the
`qtree-create` api call:

    netapp_commands :add => 'qtree-create'

in your `create` method you can now write the following:

    add 'qtree', 'q1',  'volume', 'vol1'

which will automatically invoke the `qtree-create` api call and pass all
the arguments to it.
(#33) Needed to add an additional def which referenced
self.netapp_command.
(#33) Removing un-necessary def.