Merge pull request #1206 from BrentleyJones/fixed_modals

FIX: Modal dialogs now truly center and work at all screen sizes (mobile), now with working Bootbox
Merge pull request #1213 from novemberkilo/emoji_update

Update emojis from latest gemoji
FIX: Only show undelete button when the topic is deleted
JSHINT
Fix some errors.
Each user activity filter has its own URL now.
FIX: Sometimes the total post count could be incorrect
FIX: Don't transition to when viewing a user. Just render it.
recommend latest redis
updating pt_BR translations
move squash up, remove changelog ref, etc.
add references to try.discourse for repros
better link to features category of meta
Merge pull request #1216 from prem-prakash/pt_br_translation

updating pt_BR translations
Merge pull request #1214 from nverba/patch-3

Fix some typos.
FIX: Private Message button wasn't populating username
Never render an avatar img if we know the username is invalid.
FIX: Some failing specs
Prefer unread topics in the same category
FIX: Double load on back button