noop as resource meta param

first part of #21
tested with example/noop1.yaml on CentOS 6

examples/noop1.yaml

@@ -0,0 +1,24 @@
+---
+graph: mygraph
+comment: noop example
+resources:
+  noop:
+  - name: noop1
+    meta:
+      noop: true
+  file:
+  - name: file1
+    path: "/tmp/mgmt-hello-noop"
+    content: |
+      hello world from @purpleidea
+    state: exists
+    meta:
+      noop: true
+edges:
+- name: e1
+  from:
+    kind: noop
+    name: noop1
+  to:
+    kind: file
+    name: file1

pgraph.go

@@ -729,7 +729,7 @@ func (g *Graph) Process(v *Vertex) {
 
 		obj.SetState(resStateCheckApply)
 		// if this fails, don't UpdateTimestamp()
-		checkok, err := obj.CheckApply(true)
+		checkok, err := obj.CheckApply(!obj.GetMeta().Noop)
 		if checkok && err != nil { // should never return this way
 			log.Fatalf("%v[%v]: CheckApply(): %t, %+v", obj.Kind(), obj.GetName(), checkok, err)
 		}
@@ -745,6 +745,11 @@ func (g *Graph) Process(v *Vertex) {
 			}
 		}
 
+		// when noop is true we always want to update timestamp
+		if obj.GetMeta().Noop && err == nil {
+			ok = true
+		}
+
 		if ok {
 			// update this timestamp *before* we poke or the poked
 			// nodes might fail due to having a too old timestamp!

resources.go

@@ -60,6 +60,7 @@ type AutoEdge interface {
 type MetaParams struct {
 	AutoEdge  bool `yaml:"autoedge"`  // metaparam, should we generate auto edges? // XXX should default to true
 	AutoGroup bool `yaml:"autogroup"` // metaparam, should we auto group? // XXX should default to true
+	Noop      bool `yaml:"noop"`
 }
 
 // this interface is everything that is common to all resources