Implement the PowerSpy module

[rouvoy]

• Implement the PowerSpy sensor
• Implement the proportional formula (+ an option to remove the static idle) // to be shared with the RAPL module

[mcolmant]

Two dependencies:

• bluecove-gpl: GNU General Public License (GPL)
• bluecove: The Apache Software License, Version 2.0

[rouvoy]

Does both modules are jointly required?
If so, this module cannot be included as part of the core library and has to be implemented as a package compiled separately to deal with the specificity of the GPL license.

[mcolmant]

After some test, the first one is required on Linux for using Bluetooth.
It's only a runtime dependency. The second one is used directly in the code for compilation.

Is it a problem to reference it in the build.sbt?

[rouvoy]

I think this is acceptable, we just have to check that GPL is compatible with A-GPL or if it imposes the GPL license specifically.