Add required Ruby version to gemspec

With the addition of some keyword arguments, droplet_kit will now require at least ruby 2.0.0.
Merge pull request #10 from davidcelis/patch-1

Add required Ruby version to gemspec
Create .travis.yml
Added build status

Thanks Travis <3
Removed ruby 1.9
Remove ruby head, Travis doesn't like it.
Droplets can be created with user_data and private_networking

* Add user_data attribute to Droplet resource and mapping
* Add private_networking attribute to Droplet resource and mapping
Merge pull request #8 from rbishop/user-data-and-private-networking

Droplets can be created with user_data and private_networking
Add pagination keys for actions, droplets, and images reosurce.
Update specs to use paginated resource correctly.