IPV6 Addresses are generally case insensitive but it is recommented to
store them as lowercase (https://tools.ietf.org/html/rfc5952#section-4.3)
When Terraform didn't store them as LowerCase, we got the following
error when using in DNS records:
```
-/+ digitalocean_record.web6
domain: "mydomain.com" => "mydomain.com"
fqdn: "web02.in.mydomain.com" => "<computed>"
name: "web02.in" => "web02.in"
port: "0" => "<computed>"
priority: "0" => "<computed>"
type: "AAAA" => "AAAA"
value: "2a03:b0c0:0003:00d0:0000:0000:0b66:6001" => "2A03:B0C0:0003:00D0:0000:0000:0B66:6001" (forces new resource)
weight: "0" => "<computed>"
```
There was no need for this to be the case. We now enforce lowercase on both state and also when responses are returned from the API
* Add SSH Keys to all droplets in tests, this prevents acctests from
spamming account owner email with root password details
* Add a new helper/acctest package to be a home for random string / int
implementations used in tests.
* Insert some random details into record tests to prevent collisions
* Normalize config style in tests to hclfmt conventions
Upstream in the digitalocean API, the size slug became a size
string, breaking pearkes/digitalocean.
https://github.com/pearkes/digitalocean/pull/1
This fixes compatibility for changes to that library.
closes#510
stack72