App does not work locally when offline

[gsidebo]

If you have no internet connection, our app should still work correctly when running locally. Unfortunately the app fails under these circumstances in at least a couple ways:

1. The test suite fails in tests that render the base template due to <link>/<script> tags with external urls (e.g.: <link href="https://maxcdn.bootstrapcdn.com/font-awesome/4.6.1/css/font-awesome.min.css" rel="stylesheet"/>). It's not clear why these tests are actually making the requests to those URLs instead of just rendering the page body as a string.
2. When making changes to an application that advance the state (uploading a resume, adding a video interview, completing a payment), Hubspot requests are sent in tasks. Those requests fail, and the exceptions stop execution entirely

Acceptance criteria

• Test suite runs successfully while the host machine is offline
• While offline, changes can be made to an application without breaking due to failed Hubspot requests (errors are logged, but the changes are still made)

Nice to have

• Fail the test suite if any external requests are detected. There might be a library/plugin for this?

[mbertrand]

Hubspot tasks will not run if MITOL_HUBSPOT_API_PRIVATE_TOKEN is not set. If offline, just unset this variable. Application state still seems to advance if offline.

[collinpreston]

Commenting out HUBSPOT_API_KEY allows me to run bootcamps-ecommerce locally without an internet connection. @mbertrand, do you think we can close this?

[mbertrand]

I think we can consider (2) closed, not sure about (1) - that external link is still in a couple of HTML templates.