add jenkins scripts

Move our Jenkins scripts out of Jenkins' database and into Git so that
we can have greater visibility on future changes.

Going forward, we will modify the ceph Jenkins tasks to only run these
scripts.

Signed-off-by: Ken Dreyer <ken.dreyer@inktank.com>
jenkins: add headers to scripts

Add headers and shebangs to each of the Jenkins scripts.

Signed-off-by: Ken Dreyer <ken.dreyer@inktank.com>
jenkins: fix trailing whitespace

Signed-off-by: Ken Dreyer <ken.dreyer@inktank.com>
jenkins: support autobuild key or release key

We need Jenkins to build ceph more often so we can have more testing,
but we don't want to sign these "unofficial" builds with the official
release key.

Conditionally select the release key or the autobuild key based upon the
$RELEASE environment variable. Jenkins will set this variable using a
parameter when it runs each ceph build. For formal releases, we will set
the parameter to "true".

Signed-off-by: Ken Dreyer <ken.dreyer@inktank.com>