Implementation of the module for the sensor "SGP30" #197

I could not make a push to my fork, so I propose a patch here.
applicable to a commit
210efe9

Note: a submodule is added, with the vendor's source code.

sgp30.patch.zip

p.s.
I apologize, but all my attempts to make push have not been successful.
If you share information about how you do push (repository containing large files), I will be grateful.