add timestamps to to help facilitate debugging

#### What's this PR do?
Adds timestamps to the user model, competitive story model, and donation info models. 

#### How should this be manually tested?
Create a game and play through using Postman. Donate to a project using postman. 

#### Any background context you want to provide?
Adding timestamps will help us establish the order of game events while debugging. 

#### What are the relevant tickets?
Closes #241. 
Does this need to be `Date.now()` as opposed to `Date.now`?