Add new API call to remove ZFS snapshots from a dataset / pool

REST Request:
-------------------------------
PUT /sysadm/lifepreserver
{
   "dataset" : "tank1/usr/jails",
   "snap" : "auto-2016-01-09-18-00-00",
   "action" : "removesnap"
}

REST Response:
-------------------------------
{
    "args": {
        "removesnap": {
            "dataset": "tank1/usr/jails",
            "snap": "auto-2016-01-09-18-00-00"
        }
    }
}

WebSocket Request:
-------------------------------
{
   "args" : {
      "snap" : "auto-2016-01-09-18-00-00",
      "action" : "removesnap",
      "dataset" : "tank1/usr/jails"
   },
   "name" : "lifepreserver",
   "namespace" : "sysadm",
   "id" : "fooid"
}

WebSocket Response:
-------------------------------
{
  "args": {
     "removesnap": {
        "dataset": "tank1/usr/jails",
        "snap": "auto-2016-01-09-18-00-00"
     }
  },
  "id": "fooid",
  "name": "response",
  "namespace": "sysadm"
}

src/library/sysadm-lifepreserver.cpp

@@ -131,6 +131,48 @@ QJsonObject LifePreserver::listSnap(QJsonObject jsin) {
   return retObject;
 }
 
+// Remove a snapshot
+QJsonObject LifePreserver::removeSnapshot(QJsonObject jsin) {
+   QJsonObject retObject;
+   QString dataset, snap;
+
+   QStringList keys = jsin.keys();
+   bool ok = false;
+   if(! keys.contains("dataset") || ! keys.contains("snap")){
+     retObject.insert("error", "Requires dataset and snap keys");
+     return retObject;
+   }
+
+   // Get the dataset / snap
+   dataset = jsin.value("dataset").toString();
+   snap = jsin.value("snap").toString();
+
+   // Make sure we have the dataset / snap key(s)
+   if ( dataset.isEmpty() || snap.isEmpty() ) {
+     retObject.insert("error", "Empty dataset or snap keys ");
+     return retObject;
+   }
+
+   QStringList output;
+   output = General::RunCommand("lpreserver rmsnap " + dataset + " " + snap).split("\n");
+
+   // Check for any errors
+   for ( int i = 0; i < output.size(); i++)
+   {
+      if ( output.at(i).indexOf("ERROR:") != -1 ) {
+       retObject.insert("error", output.at(i));
+       return retObject;
+      }
+   }
+
+   // Got to the end, return the good json
+   QJsonObject values;
+   values.insert("dataset", dataset);
+   values.insert("snap", snap);
+
+   return values;
+}
+
 // Revert to a snapshot
 QJsonObject LifePreserver::revertSnapshot(QJsonObject jsin) {
    QJsonObject retObject;
@@ -173,7 +215,6 @@ QJsonObject LifePreserver::revertSnapshot(QJsonObject jsin) {
    return values;
 }
 
-
 // Schedule a new scrub routine
 QJsonObject LifePreserver::scheduleScrub(QJsonObject jsin) {
    QJsonObject retObject;

src/library/sysadm-lifepreserver.h

@@ -17,6 +17,7 @@ public:
 	// List schedule snapshots
 	static QJsonObject listCron(); 
 	static QJsonObject listSnap(QJsonObject jsin);
+	static QJsonObject removeSnapshot(QJsonObject jsin);
 	static QJsonObject revertSnapshot(QJsonObject jsin);
 	static QJsonObject scheduleSnapshot(QJsonObject jsin);
 	static QJsonObject scheduleScrub(QJsonObject jsin);

src/server/WebBackend.cpp

@@ -157,6 +157,10 @@ RestOutputStruct::ExitCode WebSocket::EvaluateSysadmLifePreserverRequest(const Q
 	ok = true;
         out->insert("listsnap", sysadm::LifePreserver::listSnap(in_args.toObject()));
       }
+      if(act=="removesnap"){
+	ok = true;
+        out->insert("removesnap", sysadm::LifePreserver::removeSnapshot(in_args.toObject()));
+      }
       if(act=="revertsnap"){
 	ok = true;
         out->insert("revertsnap", sysadm::LifePreserver::revertSnapshot(in_args.toObject()));