[#390] Don't put api version in context when creating datasets in web ui

The form_to_db_schema() methods of IDatasetForm plugins were not getting
called when creating datasets in the web interface, if the IDatasetForm
plugin inherits from DefaultDatasetForm.

The reason was that DefaultDatasetForm's form_to_db_schema() method
deliberately doesn't call the method if the dataset is being created via
the API, and the package controller's new_resources() and new_metadata()
methods (for the new three-stage dataset creation) put the API version
in the context, so DefaultDatasetForm thinks it's being used over the
API.

Change the package controller to not put the API version in the context.

Fixes #390.

ckan/controllers/package.py

@@ -594,7 +594,6 @@ def new_resource(self, id, data=None, errors=None, error_summary=None):
             del data['id']
 
             context = {'model': model, 'session': model.Session,
-                       'api_version': 3,
                        'user': c.user or c.author,
                        'extras_as_string': True}
 
@@ -680,7 +679,6 @@ def new_metadata(self, id, data=None, errors=None, error_summary=None):
             # we don't want to include save as it is part of the form
             del data['save']
             context = {'model': model, 'session': model.Session,
-                       'api_version': 3,
                        'user': c.user or c.author,
                        'extras_as_string': True}
             data_dict = get_action('package_show')(context, {'id': id})