[padrino-gen] Adjust to RSpec3, and little fix

to the rake task:
* remove the formatting option
* add description to dynamic tasks
* using 'each_with_object' instead of 'inject'

to the templates:
* adjust to RSpec3 syntax
* set to be pending in the initial state

<!---
@huboard:{"order":1705.0,"custom_state":""}
-->

@tyabe Sorry, I overlooked this test. Has a different meaning between this test and other tests.
I guess this should probably be something like `expect(last_response.body).to eq('Hello World')`.