Bump to 1.8.1

Signed-off-by: Jeffrey Morgan <jmorganca@gmail.com>

Update to 1.8.0

Update to latest VirtualBox 4.3 series

Update to 1.7.0

Bump to 1.6.2

Bump Docker to 1.6.1 and the kernel to 4.0.2

Update to 1.6.0

Bump to v1.5.0

Bump to v1.4.1

Bump to v1.4.0