Change a hardcoded path into its proper constant
Change a hardcoded path into its proper constant

The function backend.UploadFile still uses "/etc/hosts" directly instead
of the existing constant; this patch fixes this.

Reviewed-by: ultrotter


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