Support for insecure POP3 (without SSL)

Ideally it would be a menu selection to select POP3, POP3S, and potentially other future protocols like IMAP if desired, but I didn't want to deal with data migration at this point.  And then I was going to have a checkbox for "Secure" (on by default, obviously), but that was very hard to word as to how it was different given everything else referred to pop3s and I couldn't change that either.  So I settled on a preference:

pop3s_polling_insecure: "Poll using plain text POP3 without SSL"

Off by default.

This makes it very clear that as to what turning on that checkbox will be, and by calling it "insecure" makes sure people will think twice before turning it on.

I have not attempted to do any of the translations of the preference, I'm ot sure how you handle that.
Bugfix: Mailing list mode disables PM emails

Emailing a PM uses the user_posted event/format, but Mailing List Mode disables emails with this format.

We work around this by temporarily using "postedprivate", and then reverting back to "posted" efter the Mailing List Mode check.
Add custom embed_by_username feature

Feature to allow each imported post to be created using a different discourse
username. A possible use case of this is a multi-author blog where discourse
is being used to track comments. This feature allows authors to receive
updates when someone leaves a comment on one of their articles because each of
the imported posts can be created using the discourse username of the author.
FEATURE: User Bookmarks Menu
SECURITY: fix XSS
BUGFIX: not binding correctly to notifications that popped up AFTER element was inserted
BUGFIX: not clearing blue notifications correctly when you have a PM
BUGFIX: fragile test corrected, stubbing is not needed here.
Use the cheap Defer queue as opposed to sidekiq for view tracking.
Gem updates, Sidekiq was old.
Merge pull request #2435 from techAPJ/add-bookmark-menu

FEATURE: Add Bookmarks menu to user dropdown
copyedits on bulk invite
Fix broken markup on invites tab
Merge pull request #2438 from techAPJ/update-invites-copyedit

Fix broken markup on invites tab
Bugfix: Mailing list mode disables PM emails (take 2)

Mailing List Mode disables normal emails, but mailing list mode does not email private_messages.

To avoid this, mailing list mode should only disable emails if they are not private_messages.

There are no tests for this commit as UserNotifications does not appear to be instantiated in the spec suite.
Version bump to v0.9.9.8
ES6: More views converted and deprecated
Always show Bookmark icon. Always show edit if the post is a wiki.
For heroku, check if necessary table exist before trying to precompile assets
BUGFIX: Correct markup syntax in locale files