1) Add `--no-install-recommends` option to `apt-get install`, this
   avoids lots of (~30MB) unnecessary packages.
2) Add `ca-certificates` package for `wget` fetching stuffs from Amazon
   S3.
3) There is no need to run `apt-get clean` for an image derived from
   official Ubuntu since they already cleaned (see also:
   http://goo.gl/B2SQRB) all the garbages produced by `apt-get`.
Signed-off-by: kfei <kfei@kfei.net>

Update changelog 7.6

See merge request !1327

Kerberos dependency

See merge request !1324

Fix note update

In some strange cases Ruby thinks `system` is not AR field but
Kernel.system call and raises exception during save. It should prevent
this random wierd behaviour.

Exception log:

```
ArgumentError (wrong number of arguments (0 for 1+)):
  app/models/note.rb:505:in `system'
  app/models/note.rb:505:in `editable?'
  app/controllers/projects/notes_controller.rb:33:in `update'
```

See merge request !1326

In some strange cases Ruby thinks `system` is not AR field but
Kernel.system call and raises exception during save. It should prevent
this random wierd behaviour
Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

Added process for green tests

Signed-off-by: Jeroen van Baarsen <jeroenvanbaarsen@gmail.com>

Fixed a lot of already defined notices

Added Code of Conduct

Add missing webhook doc for tag event

Signed-off-by: Jeroen van Baarsen <jeroenvanbaarsen@gmail.com>

remove extra upgrade details, add missing config

Signed-off-by: Jeroen van Baarsen <jeroenvanbaarsen@gmail.com>

Fix typo in the README.md for docker

Signed-off-by: Jeroen van Baarsen <jeroenvanbaarsen@gmail.com>

add details on backing up your SSH host keys

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

Validate and sanitize snippet file name

Fixes #1816

See merge request !1322

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

Fix shell commands in shell install

Fixes #1610

See merge request !1320

Dropdown icon not clickable

Fixes #1642 by using `pointer-events` property supported by [modern browsers](http://caniuse.com/#search=pointer-events)

See merge request !1319

Show files named diff

Fixes #1749

See merge request !1318

Add an extra reference to the 'shell commands' guide

The 'shell commands' guide now also has tips on opening/reading files and handling paths.

See merge request !1321

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

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