Initilization the property 'artefactplugin' of BlockInstance

This property is used in determine the path of blocktype

Change-Id: Icfeee5399d7899330efaac8fc9a323a1069aadd5
Signed-off-by: Son Nguyen <son.nguyen@catalyst.net.nz>

htdocs/blocktype/lib.php

@@ -465,6 +465,7 @@ class BlockInstance {
                 $this->{$field} = $value;
             }
         }
+        $this->artefactplugin = blocktype_artefactplugin($this->blocktype);
     }
 
     public function get($field) {

htdocs/lib/view.php

@@ -1710,8 +1710,8 @@ class View {
                 foreach($instancejs as &$jsfile) {
                     $jsfile = (is_array($jsfile) && isset($jsfile['file'])) ? $jsfile['file'] : $jsfile;
                     if(strpos($jsfile, 'http://') === false) {
-                        if ($artefactplugin = blocktype_artefactplugin($pluginname)) {
-                            $jsfile = 'artefact/' . $artefactplugin . '/blocktype/' .
+                        if ($blockinstance->get('artefactplugin')) {
+                            $jsfile = 'artefact/' . $blockinstance->get('artefactplugin') . '/blocktype/' .
                                 $pluginname . '/' . $jsfile;
                         }
                         else {