treat empty jobs & empty YAML as valid & ship empty jobs in deb/rpm (#788)

fixes https://github.com/zrepl/zrepl/issues/784
obsoletes https://github.com/zrepl/zrepl/pull/787

config/config_minimal_test.go

@@ -2,16 +2,8 @@ package config
 
 import (
 	"testing"
-
-	"github.com/stretchr/testify/assert"
 )
 
-func TestConfigEmptyFails(t *testing.T) {
-	conf, err := testConfig(t, "\n")
-	assert.Nil(t, conf)
-	assert.Error(t, err)
-}
-
 func TestJobsOnlyWorks(t *testing.T) {
 	testValidConfig(t, `
 jobs:
@@ -34,7 +26,7 @@ jobs:
     keep_sender:
     - type: not_replicated
     keep_receiver:
-    - type: last_n 
+    - type: last_n
       count: 1
 `)
 }