Add support for Google DNS API.

[fcuny]

Google recently added a new API for DNS management. This new driver
implement simple operations to create and view zones and records.

I still need to add a few more tests and probably add a bunch of things into the 'extra' for records and zones.

I'm also not familiar with other DNS drivers, so a few things might be wrong or should be done differently.

[Kami]

Can you please explicitly declare all the supports arguments instead of (ab)using kwargs?

[Kami]

@franckcuny Thanks for addressing the comments.

I'll do another review shortly and let you know if I encounter any more issues.

[Kami]

Minor thing - to prevent accidental bugs, please always use parenthesis around format string arguments.

[Kami]

Besides some minor style and consistency issues, it looks good to me.

[Kami]

Please also sync this branch with trunk so Travis build won't fail anymore.

[erjohnso]

@Kami, @franckcuny - is this good to go? I am intending to add an Ansible module and would love to take advantage of this work. :)

[Kami]

@erjohnso Sorry for the delay. I've just merged those changes into trunk.

[erjohnso]

@Kami thank you sir!