Getting a datastore.entity by key name is a pain

[jgeewax]

If I know I have a person named Jim, and I want to get Jim, I can't do a look-up by path.

What I'd like to do

dataset.get_entity(['Person', 'jim'])

or

dataset.entity('Person').get('jim')

(or with an ancestor)

dataset.entity('Person').get('jim', parent='parent key name')

What I currently have to do

key = Key.from_path(['Person', 'jim'])
dataset.get_entity(key)

[dhermes]

Closed by #393