Fixes #675 

* Made time format configurable

* Made changes to values of time_format

* Removed user restrictions on time format

* Added documentation for time-format config

* Edited changes.md

* Edited config doc

* Modified time-format explanation

* Added link to moment

* Added test to check rendered time

* Edited CHANGES and removeunncessary lines from time format checking spec

* Removed unncessary spaces

Currently translated at 100.0% (241 of 241 strings)

Translation: Converse.js/Translations
Translate-URL: https://hosted.weblate.org/projects/conversejs/translations/af/

Currently translated at 100.0% (241 of 241 strings)

Translation: Converse.js/Translations
Translate-URL: https://hosted.weblate.org/projects/conversejs/translations/af/

* Fixes the bug in displaying chat status during private chat(message carbons)

* Adds fix#628 to ChangeLog

* Changes Log added to version 3.0.1

* Makes the string alphanumeric

* Orders the logs with ticket number

Functions need to be bound.

- Document `optional_plugin_dependencies`
- Also make `converse-headlines` an optional dependency of `converse-dragresize`

updates #805

so that we don't confuse it with the case where it was manual.

Otherwise other plugins don't know whether the message was forwarded or not.

After bookmarking a room for which a nickname is required, return to the nickname form.

The padding didn't appear consistent across browsers.

Otherwise we receive HTML5 notifications for MAM messages because they can't be
identified as such.

since I couldn't find a way to do this with only CSS.

- immediately show chat box (sometimes fetching features takes long)
- add timeout for fetching features
- don't register scroll handler twice for chat rooms.