Fixes #5116

Comments expansion refactoring

Adding bootstrap-markdown editor

If you look at comment expand process with javascript debugger, you
will notice that at first comments get added to existing stream ("add"
event handler of model.comments gets launched because of model.comments.fetch).
Then the comment stream gets empty and then filled by the postRenderTemplate
handler.

This patch removes comments rerendering on the expansion. The fetching process is
changed so that older comments are added to the correct place, so the order
looks nice without rerendering. Thus, unnecessary job of rerendering is avoided.

Add 'no posts yet' message to empty streams

Add role='alert' to alerts

Disable animations in poltergeist

Bump poltergeist

Fix up the meaning of the name parameter in mention

Fix command in changelog

The desktop frontend now treats the "name" parameter of mention as
a string to display unconditionally. But the Diaspora::Mentionable
renders mentions the different way: "name" is treated as a fallback
string which is rendered only if the person's name is unavailable.
This reflects on the mobile version ATM. This patch makes it behave
the same way as the current desktop version does.

Upgrade devise to 4.2

Remove inline notifications javascript

Fix settings page after submit