Add security tips about file and paths

These are some extra guidelines to guard against code execution and path traversal.

See merge request !1317

Speed up omniauth AddIdentityTable migration

https://dev.gitlab.org/gitlab/gitlabhq/issues/1810

See merge request !1315

Unicorn workers

See merge request !1316

Unicorn advice

See merge request !1314

Add 'grace time' behavior to Sidekiq MemoryKiller

The previous iteration of the memory killer did not give 'large'
jobs much of a chance to finish. This caused them to come back after
each restart, leading to another memory-induced shutdown. By adding
some 'grace time' between the moment we detect a memory peak and
the moment we start shutting down, we hope to give Sidekiq a chance
to get whatever causes its memory to grow 'out of its system'.

See merge request !1313

Drop vagrant from issue tracker guidelines

Is this the preferred method of reproducing an issue? If yes, disregard this MR.

\cc @sytses @marin

See merge request !255

Move sidekiq debug docs to development folder

Attachment url should not be overwritten

Fixes #1786

See merge request !1308

Improve Monokai highlight style to match original

The current monokai style is not very true to the original and lacks colors for certain syntactic items as mentioned in ticket https://github.com/gitlabhq/gitlabhq/issues/6855. This change's goal is to bring the monokai highlight style in line with the original design from http://www.monokai.nl/blog/2006/07/15/textmate-color-theme/

Before:
![monokai-old](https://gitlab.com/uploads/klowner/gitlab-ce/ce96c7d7c2/monokai-old.png)

After:
![monokai](https://gitlab.com/uploads/klowner/gitlab-ce/b257a8143a/monokai.png)

See merge request !238

Improve activity UI

See merge request !1311

Small fixes

Improve application stability over unexpected cases

See merge request !1310

Async services

Fixes #1814

See merge request !1312

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>

Author filter for issues and merge requests pages

This is first step in implementing #1604

See merge request !1309

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>

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

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

Fix merge request lock problem

Merge Request lock problem
MR can be stuck in lock state if satelitte timeout >= unicorn timeout.

Issue explanation:

* Person press Accept button
* unicorn worker starts, lock MR and trigger satellite
* satellite does merge but very long (30 seconds)
* unicorn timeout reaches earlier then satellite timeout
* unicorn kills worker because of timeout leaving MR in lock state.

Fix:

* set locked_at date
* if MR was locked for too long - close it automatically

- - -

Fixes #1674

See merge request !1306

Add snapshot backup tips

See merge request !1307

This reverts commit b37b71d8, reversing
changes made to 42a1d808.