Specs for existing `Fog::Bin` interface

Prepartion for fog/fog-core#105
Detailed checks for `Brightbox` class
Mark additional DigitalOcean test as pending

See: https://github.com/fog/fog/pull/3304
Disable ALL DigitalOcean tests until fixed

There appears to be a glitch in the test suite such that running
`bundle exec rake travis` passes locally without executing the DO tests
but they are running on Travis itself.

So fed up playing whackamole with failures. They are off until the
broken code is fixed.

See https://github.com/fog/fog/pull/3304

This reverts commit 9b7b8fd49000d6ccb82bf2a731b78d6974977e67.
This reverts commit fa9254ba8ddba408617553f0a877bdea64ec80d5.
Remove Rackspace references until reinstated

Tests were based on v1.25.0 which included Rackspace support. It was
extracted into a module and not correctly referenced so is no longer
present on master.

This commit should be reverted and the specs passing before the next
release.
[digitalocean|compute] add private_networking attribute
[digitalocean] reenable tests

closes #3330
[Openstack|Tests] Add rake subtask for testing only Openstack
[Openstack|Compute|Server] Add test boot from block_device_mapping
[Openstack|Compute|Server] Add test boot from block_device_mapping_v2
[Openstack|Compute|Server] Rewrite block_device_mapping to support

Old support did not properly handle multiple volume attachments for block_device_mapping_v2
V2 support is much different and should be requested with the proper key name rather than being merged into block_device_mapping
Reinstate Rackspace "bin" checks

Following v1.25.0, Rackspace support was extracted into a module however
it broke support to the original fog API.

The Rackspace module is currently disabled until a few key files are
replaced.

This adds tests that worked against v1.25.0 that checks that `rackspace`
is registered correctly. See https://github.com/fog/fog/pull/3326

This reverts commit 9717002fd3d18aef0c359fc52ac704894a34dac0.
Revert "Moving Rackspace logic to fog-rackspace"

This reverts commit d6ecb19d24503d432d84042753afa1304648d055.

Conflicts:
	fog.gemspec
More specs to cover `Fog` methods
[vSphere]: Add full path to cluster