Update superagent to 3.4

[ktonon]

Not sure about this one as updating caused a test to break:

  local
    1) should default to scope *:*:*
    ✓ should resolve with token the LMS returns
    ✓ should dedupe concurrent requests for the same scope
    ✓ should not dedupe concurrent requests for different scopes
    ✓ should cache tokens per scope
    ✓ should re-fetch tokens after expiry
    ✓ should account for clock skew from server when determining expiry


  6 passing (68ms)
  1 failing

  1) local should default to scope *:*:*:
     Error: Nock: No match for request {
  "method": "POST",
  "url": "http://localhost/d2l/lp/auth/oauth2/token",
  "body": "scope=%2A%3A%2A%3A%2A"
}
      at end (node_modules/nock/lib/request_overrider.js:260:17)
      at OverriddenClientRequest.RequestOverrider.req.end (node_modules/nock/lib/request_overrider.js:160:7)
      at Request._end (node_modules/superagent/lib/node/index.js:944:9)
      at Request.end (node_modules/superagent/lib/node/index.js:745:15)
      at Timeout.completeRequest [as _onTimeout] (node_modules/frau-superagent-xsrf-token/src/index.js:21:15)

First I tried updating nock, didn't help (I left that change in anyhow). Then I made the change to the spec, which caused the test to pass. Although I don't understand the test to begin with

[coveralls]

Coverage remained the same at 77.5% when pulling b49f1c5 on ktonon:master into 84112a7 on Brightspace:master.

[omsmith]

The qs module superagent uses was updated a whole lot. Should be compatible, but I'd just want to double check the platform accepts this encoding to be sure. I'll give that a go shortly.

[omsmith]

Works as far as I can tell