stub to use Dummy platform instead of using Platform.platform~

[#55682936]

Signed-off-by: Jeffrey Peckham <peckham@pivotallabs.com>
Avoid meta-programming to instantiate platform

[#55682936]

Signed-off-by: Jeffrey Peckham <peckham@pivotallabs.com>
Separate namespace from adapter for ubuntu platform

[#55682936]
Separate plaform namespace & adapter responsibilities
Prefer rspec double over Dummy platform