[bug 882426] Username in profile URL's
Fix profile URLs for non-alphanumeric usernames
Add comment to profile view
Wiki and Product APIs. Added for Yaocho.

This squashes the following commits:

ae0ff3e Document viewing and browsing API.
4dc7d5f WIP on products API.
a3f7c3a Changes for yaocho topic browser.
e623a8b API Accept-Language
a201ddf Test and fix LocaleNegotiationMixin.
1c041fa Filter out non-useful articles.
b62bc25 test language negotiater
9b3ab92 Test Product.path
6419ec2 Localize topic names.
6f96637 idk, something.
9b7988a Feedback
41b0adc More feedback.
e25cb56 Versioned api and bool() querystrings.

Document viewing and browsing API.

WIP on products API.

Changes for yaocho topic browser.

API Accept-Language

Test and fix LocaleNegotiationMixin.

Filter out non-useful articles.

test language negotiater

Test Product.path

Localize topic names.

idk, something.

Feedback

More feedback.

In particular, less funky queryset manipulation and more docstrings.

Versioned api and bool() querystrings.
Error handling in profile view
[bug 1030532] Needs change comment now cleared.

When the box is unchecked and the form is submitted, the comment
is now cleared.
Merge pull request #2005 from dean/revision-persist-1030532

[bug 1030532] Needs change comment now cleared.
[bug 1006574] Top contributors infrastructure.
[bug 1006574] Implement initial UI for top contributors.

* Implemented the top contributors view and template
* Implemented the top contributors on the Community Hub landing page
[bug 1030348] Fixes issue with Topic selection Dropdown
[bug 971782] JS fix for data bucketing (weekly, monthly).

The bucketing implemented in Rickshaw does not like missing data
for any dates. It wants explicit 0s. This zero-fills all the
dates.
[bug 987337] Show topic descriptions on topic pages.
[bug 1032175] Update error message
[Bug 1031906] Update error message in users/forms.py
[bug 1001145] Track usage for canned responses
[bug 984007] Fix localization status on L10N dashboard
[bug 1019649] Add news section to community hub.
[bug 970214] Send a weekly "Ready for review" digest
[Bug 1033339] Fix latest_version in product view.

This is a partial revert of 64d896f1d7524a4b45648a10ee2d99988eb49e83
[bug 682235] Encourage kindness when asking questions