Nayuos - ebuild, bashrc improvement, add promisses
This MR is continuation of !88 (closed) which was made from a private fork.
Commits by @iv reviewed by @tc
- Automatically increment ebuilds revision number.
 - Add Chromium browser policies (to use an ebuild which set Duckduckgo as default search engine).
 - Improve git configuration in bashrc (export environment variable instead of creating an alias).
 - Export EDITOR environment variable in bashrc (so that git does not complain about not finding nano).
 - Keep portage_stable overlay clean (stash changes after building).
 - Remove nodejs package which is causing troubles