Oliver Smith authored Feb 20, 2020 and Alexey Minnekhanov committed Feb 24, 2020

While at it, also remove unnecessary "#!/usr/bin/env python3" in files
that only get imported, and adjust other empty/comment lines in the
beginnings of the files for consistency.

This makes files easier to read, and makes the pmbootstrap codebase more
consistent with the build.postmarketos.org codebase.