AArch64 support

AArch64 support

- spec: change hardcoded x86_64 arch to current platform arch;
- spec: bump dependency manager version from 0.5.0 to 0.5.4,
  the first golang/dep release to include arm64 (aarch64) bins;
- Dockerfile(s): download arch-specific golang/dep binaries;
- Dockerfile: Instead of pulling CentOS base images from dockerhub,
  create them from scratch from the official SIG-cloudinstance repo:
  http://artifacts.ci.centos.org/sig-cloudinstance/
- spec: Bump minor RPM version;

Co-authored-by: Jimmy Lafontaine Rivera <lafonj@gmail.com>
Signed-off-by: Alexandru Avadanii <Alexandru.Avadanii@enea.com>
Change-Id: Id201364bd38ef5af2756a8b5083e8a1cb45976a1