Create a stats module to keep track of a user's practice stats

[milindvishnoi]

Overview

We'll create a StatsModule that deals with the logic and storage of user stats. This module can be be used from across the app.

The Stats module will take care of:

• [ ] Percentage Of Correct Questions #18
• [ ] # of Questions answered #19
• [ ] Time spent practicing #20

Behaviour

When a user answers a question correctly, the stats module would behave as follows:

• For the MathConcept and the Total Stats:
  • Update the total count
  • Update the time spent
  • Update the correct count

[ArsalaBangash]

Instead of each type of question, let's refer to it as each math concept.

Also, this issue is pretty broad because it reads "Stats for each type of question", and then in the overview, it says "To display stats..."

You can clarify what this issue is for by specifying if this is for the stats page that displays stats OR for the creation of a stats module that would generate these stats.

In my estimation, we would probably need both issues.