Feature: Basic usage metrics for mapo-api

[bensivo]

I should be able to see basic usage metrics for mapo-api.

Metrics we care about:

• Number of requests for each endpoint
• Response time for each request (aggregates are okay)
• Hardware metrics for the nodes running mapo (cpu, mem, storage, network)

Feature:

• These metrics should be viewable easily from anywhere (web browser)
• These metrics should outlive any single instance of the mapo-api
• These metrics should have some kind of retention interval
• The solution should be cheap