* Added coding style modes to SimpleMDE

* Moved the CodeMirror addon from simplemd to codemirror directory

Initially proposed by #2376 and fixes #3068 as well.

Also changes the avatar from a jpeg to a png, to allow for
transparent background. The indexed png is also smaller in size.

Note that at the moment the default avatar is only used when
the user requested a custom avatar and the custom avatar file
is not found (should never happen).

In the future the default avatar could be used as a default
return when by-mail avatar lookups fail too (both gravatar
and libravatar support passing a default)

- Update language choose dropdown to fit more languages

* Add and start jQuery AreYouSure

* Update SimpleMDE to 1.10.1 for `forceSync` support

* Forgot to remove old version SimpleMDE 1.10.0

* formatting -.-

- add border-radius to filter list items
- use color as background of label for issue/pull view page

By adding a Japanese font in the less file, easier to see the display in
Japanese.

Both are possible on explore and admin panel

Collaborators have write access as default, and can be changed via repository
collaboration settings page to change between read, write and admin.

- Allow to delete current avatar