Add a helper function to the RAPI client
Add a helper function to the RAPI client

This adds a new method WaitForJobCompletion that can be used for
client who are not interested in the entire job log, just in its
completion status.

Signed-off-by: Iustin Pop <acf83a5274f31a43af6b914614365999469c1a31@google.com>
Reviewed-by: Iustin Pop <acf83a5274f31a43af6b914614365999469c1a31@google.com>
Reviewed-by: René Nussbaumer <bc755ac45a0e799d1d490cba76febc56d80cc5fc@google.com>

andir/ganeti,ganeti-github-testing/ganeti-test-1,apyrgio/ganeti,grnet/snf-ganeti,mbakke/ganeti,mbakke/ganeti,grnet/snf-ganeti,ganeti-github-testing/ganeti-test-1,dimara/ganeti,apyrgio/snf-ganeti,ganeti/ganeti,andir/ganeti,yiannist/ganeti,onponomarev/ganeti,bitemyapp/ganeti,apyrgio/ganeti,yiannist/ganeti,andir/ganeti,ganeti/ganeti,yiannist/ganeti,apyrgio/snf-ganeti,leshchevds/ganeti,mbakke/ganeti,bitemyapp/ganeti,onponomarev/ganeti,ganeti/ganeti,leshchevds/ganeti,dimara/ganeti,leshchevds/ganeti