kernel: various fixes

kernel: various fixes

- rename ARCH to DEB_ARCH to avoid overriding kernel ARCH variable in
  Makefile
- rename SHA1 to GIT_COMMIT, we do not set SHA1 anywhere
- generate the kernel config with a script
- deb files are stored in ../, clean ../, clean-up first to upload only
  new ../*.deb files
- rpm files are stored in ~/rpmbuild, clean-up first to upload only new
  rpm files
- remove precise from default distros as we do not seem to have any huge
  precise machines lying around at the moment
- add trusty to default distros

Signed-off-by: Boris Ranto <branto@redhat.com>