reformat scopedVarArray (This is a port of PR #29)

Author: Stephen McCann

src/datasource.ts

@@ -295,7 +295,7 @@ private injectVariables(target, scoped, range) {
     //scoped variables inject
     for(let k = 0; k < scopedVarArray.length; k++) {
         scopedValueArray.push(scoped[scopedVarArray[k]].value);
-        scopedVarArray[k] = "${" + scopedVarArray[k] + '}';
+        scopedVarArray[k] = "$" + scopedVarArray[k];
 
     };
     //local variables inject (user variables)