Fix various issues in the GitHub client

- Filter out pull requests from issues
- Include a count of pull requests
- Be sure to include commits and issues which fall within the end date
  of the given period
- Use OctoKit.auto_paginate and remove all the manual paging code
Add docs for GitHub
Merge pull request #15 from 25-ventures/feature/github-tweaks

Feature/github tweaks
Add Quickbooks Online integration

- omniauth-quickbooks has an issue right now that a pull request has
  already been made to fix. Once it is fixed, the dependency can live
  here. Until then, it needs to be added manually to the main app.

- Uses a reduced data set for the reports, more can be added in the
  future.