Fixes #749. Add a "My Activity" page.

[miketaylr]

And refactor a bunch of stuff to make it work.

Note there's more work to be done to make our components composiable/modular. This is a fest step towards making that happen with pagination. I'll likely re-do some of what I've done here with this Mixin pattern when we add sorting/per page dropdowns. But it works, so let's put it up for review.

r? @karlcow for Python/HTML/CSS bits
r? @hallvors for JS/HTML/CSS bits

And anybody who has feedback on visual design is welcome to provide that. I'll push to http://staging.webcompat.com/me

[miketaylr]

Tests are failing, so it's possible I screwed up the merge conflicts. Let me push some fixup commits.

[miketaylr]

Alright, tests are green. Fire ze (review) missles. 🚀

[magsout]

👍🎉💕

[magsout]

@miketaylr an error on staging:

[miketaylr]

Hmm, thanks. Will look at it.

[miketaylr]

(silly mistake)

[miketaylr]

(I just rebased against master and force pushed).

[miketaylr]

One last failure, related to the fixture file labels.6665c4820456e6a813dcbbdddd690ffc.json being missing. Will take a look tonight or tomorrow, my brain is too jet lagged right now 😕

[miketaylr]

Ah, now I get it. I rebased and master has the ?per_page=100 hack for the labels endpoint. Fixture files want a hashed encoding of GET params (to be able to serve different states). Let me see if renaming the file doesn't fix it.

[miketaylr]

OK, it seems like everyone is on board with these changes, and tests are passing. I'm gonna go ahead and merge this now. We can clean up the few issues noted here when we iterate on the activity page and add in the other components as mixins.