Allow developers to upload sources of an Addon version (bug 540028)

[yohanboniface]

Do not review yet (but comments always welcome ;) ).

Ref: https://bugzilla.mozilla.org/show_bug.cgi?id=540028

TODO

• restrict source file access
• change file link in form widget (or do we want another widget than FileField?)
• add field to "Upload New Version" form
• add field to "Submit a new addon" form
• add field to "Upload a new file" form
• add download link in the "editor page"
• automatically flag addon for 'admin review' when a source is added
• style forms

From Jorgev:

• In the review page, the Download Source option should only be available to Admin Reviewers (group 50005). I would also use "Additional sources" so it's clearly distinguishable from the sources in the XPI.
• In the upload forms, the source code form should appear after the upload and validation for the XPI succeeds. Otherwise it might confuse developers.
• I would change the label "If your add-on contains binary or obfuscated code other than known libraries, upload its sources for review. Read more about the source code review policy." The 'Read more' text should link to https://addons.mozilla.org/developers/docs/policies/reviews#section-binary and open in a new tab.

[davidbgk]

I thought the cleaned_data would always have a 'source' key(?)

[yohanboniface]

You're right. And BTW, .get(xxx, None) doesn't make sense as it's the default behaviour :p

[yohanboniface]

We need to land #110 before merging here

[davidbgk]

r+ when ready for landing