When exercising the polyfill in Firefox, the invalid JSON parsing error
will cripple the test suite, causing cascading failures in Mocha HTML
output as well as cause failures in unrelated tests.

The code fix was proposed #157 but we decided not to pull it since it's
a Firefox bug and Firefox now ships with native fetch anyway. Instead,
we avoid running that test as part of our polyfill test suite.

Mysteriously, it doesn't implement it.

This is opposed to checking for native ArrayBuffer because the polyfill
will only define `arrayBuffer()` methods if Blob is available.

Before, in browsers that had native `fetch` implementation the polyfill
code was never exercised by the test suite. This ensures that both
implementations are exercised.

If someone just cloned this project, they might be tempted to
`script/server` and try to run the test suite immediately. That won't
work, because they have to run `make` first to obtain all npm and bower
dependencies. However, they would get a blank HTML page which would be
confusing because it's not immediately apparent what they did wrong.

Now, an error message is rendered that suggests you should run `make`.

https://travis-ci.org/github/fetch/jobs/88862914

Allow making a POST request with an ArrayBuffer body

Run Sauce Labs CI for pull requests

[ci skip]

Closes #209, fixes #185

https://fetch.spec.whatwg.org/#dom-response-clone

Remove moot `version` property from bower.json

Every request now goes through general-purpose `saucelabs-api` command
which, by default, dumps the data in line-based format suitable for
parsing on the command line. If `--raw` is passed, raw JSON is returned
instead.

Disable Travis' own Sauce Labs integration

Use absolute URL in Response.redirect test

Avoids an issue where native implementations resolve and expand the URL.

Support Response.error() and Response.redirect()

Reject the Promise returned by fetch() when Request ctor throws

Fix incorrect assertion

Remove superfluous assignment

Closes #205.

Add webpack usage link.

Allow passing a Request instance to Request constructor

The fetch spec instructs that Request should throw a TypeError when
given a Request with an already consumed body, but Chrome's
implementation doesn't respect that yet.