Add a few aliases for startup/shutdown
Add a few aliases for startup/shutdown

These aliases are widely used to think of these operations and save some typing
too. Even though there is some thought to make start/stop the default operation
name I don't think this should happen for 1.2, for now adding it as an alias is
fine.

Reviewed-by: iustinp



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