[Brightbox] Round out fog-brightbox gem

Adding Gemfile, Rakefile, README and licence information.
[Brightbox] Use minitest in Brightbox module

Includes a simple test of Compute class.
set custom application/version for google compute
use custom and fog user agent
Return empty set on route53 if no records match
Merge pull request #2754 from erjohnso/google-ua

[google|compute] Allow seting custom application/version for requests
Merge pull request #2752 from brightbox/brightbox_module_updates

[Brightbox] Updates for gem/module
Minitest picks up tests in provider modules
[Brightbox] Remove dependency on .fog in test

This isolates the tests from the values in `Fog.credentials` which is
based on the contents of `~/.fog`

Underlying problem is that the code (and many others) rely on the Fog
global making it too tightly coupled to the environment hence having to
stub.

Full issue: https://github.com/fog/fog/issues/1390

This will probably be a repeating pattern we need to work on to DRY up
so every test from every provider doesn't include this setup workaround.
Merge pull request #2755 from fog/test_providers

Minitest picks up tests in provider modules
Merge pull request #2757 from josacar/bug/fix-route53-empty-recordset

[dns|aws] Return empty set on route53 if no records match on mock