opt: using google/cloud-storage.

[sinkcup]

#74

[zoidyzoidzoid]

0.21 of google/cloud goes back to the 22nd of February 2017, while 1.3.0 of google/cloud-storage only goes back to the 15th of December 2017. Even 1.0.0 only goes back to March 2017.

We should maybe try support from 1.0.0 onwards, and test each latest minor version at least, and there aren't too many so we can just add them to the env matrix in .travis.yml?

[sinkcup]

@zoidbergwill good idea! I have changed it.

[zoidyzoidzoid]

I think we should do>= 1.0 <1.4, because it is safer.

[sinkcup]

fine, I have changed it again.

[zoidyzoidzoid]

Looks great to me! Thanks. 👍