Began work on rewriting parser without object orientation

Parsing is expensive, if the parse tree can be stored on the DB it can 
save a lot of compute time, but mongo can't store Classes, so we 
re-write without classes

app/imports/parser/parseTree/constant.js

@@ -0,0 +1,18 @@
+const constant = {
+  create({value, valueType}){
+    if (!valueType) throw `Expected valueType to be set, got ${valueType}`
+    return {
+      type: 'constant',
+      valueType,
+      value,
+    }
+  },
+  compile(node){
+    return node;
+  },
+  toString(node){
+    return `${node.value}`;
+  },
+}
+
+export default constant;