build: fuel-main: Decouple patches, Makefile.

build: fuel-main: Decouple patches, Makefile.

Tested in armband, with very small adaptions.

Use `git apply` and/or `git am` in favor of `patch`.
Change patches from old context format to unified diff.

This change allows us to decouple Makefile and patches.
This means we no longer have to manually stage touched files
before committing them to git.

Possible improvements:
- move patches to separate dir and add ordering info (prefix);
- merge patches (currently we have one per touched file);

Remove obsolete (unused?) patch:
- fuel-main_docker_version.patch

Change-Id: I5b621370993b259779c813b47105f632948e6da7
Signed-off-by: Alexandru Avadanii <Alexandru.Avadanii@enea.com>