Implement authentication through a Facebook flow

[julienw]

Closes #24

[julienw]

feedback? @ferjm

Now I need to work on tests and clean up some style :)

[julienw]

BTW I use https://github.com/julienw/sensorweb-login-website to start my login flow. Here are the informations for my client with the hardcoded JWT:

name: julien
key: 7c91e8d619046ad7
secret: efa0a85e98bfc7929e66a18e14db5cdae4fce6517dc48e3c138fcf3d207b94b3af883985a7134adef94790b59acdb1be220011f8aff903cab8729cbdb45005ff
authRedirectUrls: {http://localhost:10000/token.html}
authFailureRedirectUrls: {http://localhost:10000/tokenFailure.html}

[coveralls]

Coverage decreased (-0.5%) to 85.561% when pulling df6d2a9da377658d73a57cb6a4e088c653d57b5c on julienw:user-management-3 into 4900a9747f70b065ecccc6a4e6d4049531f006a5 on mozilla-sensorweb:master.

[julienw]

I haven't checked if travis/circleci works yet. I think circleci doesn't because I haven't adapted the config file yet.

also there is a breaking change: the endpoint to login changed, so we'll need to update the admin panel.

[coveralls]

Coverage decreased (-0.5%) to 85.561% when pulling 00649fa2d7fbe9910bd7bb3a13ef8adc7e747d0c on julienw:user-management-3 into 4900a9747f70b065ecccc6a4e6d4049531f006a5 on mozilla-sensorweb:master.

[julienw]

CircleCi is green now, so @ferjm r?

If you review only the changes from last time, please note I reverted some of the lint changes I did in the first patch. So if you see semicolons disappearing, dont be surprised :)

[coveralls]

Coverage decreased (-0.5%) to 85.561% when pulling 2b9339389922255dd16a0b66837d57f4f66b5fa6 on julienw:user-management-3 into 4900a9747f70b065ecccc6a4e6d4049531f006a5 on mozilla-sensorweb:master.

[coveralls]

Coverage decreased (-0.4%) to 85.6% when pulling c5a5f6beb5b31f6803b4df6c92ff568eac9011b9 on julienw:user-management-3 into 4900a9747f70b065ecccc6a4e6d4049531f006a5 on mozilla-sensorweb:master.