datastore: properly form deferred keys

[stephenplusplus]

Fixes #1497

Keys need to be properly formed for the API. We were skipping a step with deferred keys.

[stephenplusplus]

@sfbaltaci -- would you mind trying this out?

$ npm install --save stephenplusplus/gcloud-node#spp--1497

[5o50]

sure, i just have a problem when trying to install your branch.
I updated npm and stuff

 👉  npm install --save stephenplusplus/gcloud-node#spp--1497
npm ERR! addLocal Could not install /var/folders/0_/48d676fd5tldy0mjv1dxkbyc0000gn/T/npm-66124-83f10e85/git-cache-29227a15/67ccd9a66251327cc5acfd20a411c120c1055b6c
npm ERR! addLocal Could not install /var/folders/0_/48d676fd5tldy0mjv1dxkbyc0000gn/T/npm-66124-83f10e85/git-cache-53ed583b/67ccd9a66251327cc5acfd20a411c120c1055b6c
npm ERR! addLocal Could not install /var/folders/0_/48d676fd5tldy0mjv1dxkbyc0000gn/T/npm-66124-83f10e85/git-cache-76ceb629/67ccd9a66251327cc5acfd20a411c120c1055b6c
npm ERR! Darwin 15.6.0
npm ERR! argv "/usr/local/Cellar/node/6.3.1/bin/node" "/usr/local/bin/npm" "install" "--save" "stephenplusplus/gcloud-node#spp--1497"
npm ERR! node v6.3.1
npm ERR! npm  v3.10.6

npm ERR! No version provided in package.json
npm ERR! 
npm ERR! If you need help, you may report this error at:
npm ERR!     <https://github.com/npm/npm/issues>

npm ERR! Please include the following file with any support request:
npm ERR!     /Users/baltaci/Desktop/api-svc/npm-debug.log

[stephenplusplus]

Woops, sorry. I forgot with the new restructured repo, it's not a one-liner to install from a PR branch anymore. The most straightforward way to try it out is by cloning:

$ git clone https://github.com/stephenplusplus/gcloud-node -b spp--1497
$ cd gcloud-node/packages/compute
$ npm install
$ npm link

# cd to your project
$ npm link @google-cloud/compute

Where you're using Compute:

-var compute = gcloud.compute();
+var compute = require('@google-cloud/compute')();

Sorry for that being so complicated :\

[5o50]

It works !!
Thanks for your reactivity 💯

[nodemon] starting `node server.js`
info: api-svc ✓ PORT: 3000 PID: 69190 NODE_ENV: staging
INPUT 318
318 RESULTS
info: POST /graphql? 200 5002ms

[coveralls]

Coverage remained the same at 100.0% when pulling 67ccd9a on stephenplusplus:spp--1497 into 3cfc68c on GoogleCloudPlatform:master.

[stephenplusplus]

Awesome, thanks for reporting and testing!

@callmehiphop PTAL