Implement Syncback to support converting Roblox files to a Rojo project (#937)

This is a very large commit.
Consider checking the linked PR for more information.

rojo-test/syncback-tests/nested_projects/expected/nested.project.json

@@ -0,0 +1,15 @@
+{
+  "name": "Nested",
+  "tree": {
+    "$className": "Configuration",
+    "BoolValue": {
+      "$className": "BoolValue",
+      "$properties": {
+        "Value": true
+      }
+    },
+    "StringValue": {
+      "$path": "string_value.txt"
+    }
+  }
+}