feat: bearer token support

This PR does two simple things:
* look for an 'authToken' field in the sign-in response, and
    store this as hoodie.account.authToken
* send an 'Authorization' header with 'Bearer ' + that token in
    each request to the hoodie-server.

This PR goes together with a PR on the hoodie-server repo, which
at the HAPI level, will:
* strip the couchdb cookie and add it into the JSON response of
    signIn requests.
* read the Authorization header to look for a token of the form
    'Bearer ...', and create a cookie header from the '...', to
    send to the couchdb layer.

set authToken from config at page load

fix https://github.com/hoodiehq/hoodie-server/pull/288#discussion_r17104243

BREAKING CHANGE:

Hoodie is not using cookies for authentication anymore and relies
on hoodie-server@^2.0.0

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This commit was sponsored by The Hoodie Firm.
You can hire The Hoodie Firm:

http://go.hood.ie/thehoodiefirm
chore(npm): removed karma packages temporarely

* * *

This commit was sponsored by The Hoodie Firm.
You can hire The Hoodie Firm:

http://go.hood.ie/thehoodiefirm