Merge pull request mozilla#587 from magopian/1170266-license-optional… …-for-unlisted-addons Don't require a license when editing an unlisted addon (bug 1170266)

Revert "Changed the download button CTA for non-Fx users. (bug 1170736)" This reverts commit 1db0172.

Update wording on t-shirt form. 

Open the links for the 'unlisted ui is in beta' in a new tab (bug 117… …4012)

bump the amo-validator to 1.7.5 

Merge pull request mozilla#573 from magopian/1169574-find-MANIFEST-fi… …les-in-XPIs Find XPIs that have a META-INF/MANIFEST.MF file (bug 1169574)

Merge pull request mozilla#572 from mozilla/revert-570-1165503-update… …-django-mozilla-product-details Revert "Update django-mozilla-product-details (bug 1165503)"

Don't display the 'unlist' option in the devhub unless the flag is ac… …tive (bug 1168596)

Merge pull request mozilla#568 from magopian/1166978-better-validatio… …n-messaging-bis Better validation messaging on add-on submission (bis) (bug 1166978)

Don't fail on non-ascii filenames when bulk signing (bug 1162058)