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.
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.
Allow all /my URLs

Previously, URLs like /my/activity/posts were denied. This change allows those URLs.
Let Plugin-Outlet Render inner template data

 - allows passing of template data to the plugin-outlet to be rendered if no plugin is using that slot
 - acts as a fallback when no plugin is found
 - allows wrapping of existing features inside a plugin-outlet that then plugins can overwrite with their own behaviour
 - backwards compatible
 - uses invisible emberviews (as Ember.Component does)
 - the template has full-access to the controller and view, should be totally transparent
Merge branch 'add_custom_embed_by_username' of github.com:justinleveck/discourse into justinleveck-add_custom_embed_by_username

Conflicts:
	config/site_settings.yml
Merge branch 'justinleveck-add_custom_embed_by_username'
Don't disable the composer's submit button. Let it be clicked to cause validation error messages to show.
FIX: chrome password manager, for reals fix
FIX: allow saving profile preferences when name field is blank
Merge pull request #2449 from ligthyear/plugin-outlet-defaults

Plugin-Outlets-defaults for template overriding
Merge pull request #2408 from peternlewis/pop3_insecure

Support for insecure POP3 (without SSL)
FIX: New action arriving in stream via message bus
FIX: topics in private sub-categories were visible to everyone on the categories page
ES6: Just a couple of views
misc log in vs. sign in copy fixes
improve hint on admin user search
normalize to search.title for search help
Merge pull request #2444 from riking/my-fix

Allow all /my URLs
BUGFIX: trust_level_0 group not including trust_level_1
BUGFIX: manual trust level change not adding user to groups
BUGFIX: system not in correct trust level groups
Fix broken merge