Allow for fuzzy top/bottom brightness and adjust speech percentage

[Fmstrat]

Description:

Currently the system does not allow for adjusting percentage brightness above 100% or below 0%. This allows users to speak in fuzzy terms, I.E. if the brightness is at 80% and a user asks to increase brightness by 30%, it will jump to 100% vs erroring. Also, the response from MyCroft was using brightness levels of 0-255 vs 0-100%. This was adjusted as well.

Checklist:

• [ X ] Code is Python 3.x compatible
• [ ? ] Travis is passing tests Your PR cannot be merged unless tests pass
• [ ? ] No PEP Bot Errors or Issues

(Note: I believe the PR needs to start to know about tests)

[Fmstrat]

Sounds good, happy to amend the commit to do what is described.

[Fmstrat]

@stratus-ss Commit has been amended, let me know what you think!