Add google cloud datastore Lock implementation

[amura2406]

Hi, I just added google cloud datastore implementation, I use it on my project
Just thought that you want to include it in your original repo.

Thanks

[adrai]

Can index.yaml be moved somewhere else? i.e. test directory?

[amura2406]

yes, certainly

[amura2406]

already move the file to test folder

[adrai]

Can you also extend the readme?

[adrai]

btw: Can you please use the use function Lock.use instead of require (like the other db implementations)?

[amura2406]

done

[adrai]

Is the datastore “testable” via travis or should we skip it in the tests?

[nanov]

It should be. Might take a deeper look later on today.

[amura2406]

I think so too, but I haven't got lucky with cloud datastore emulator in the past few days

[adrai]

else it should be skipped here