Double check blog post mention

See merge request !1347

Fix 500 on MR diff page after merge and branch was removed

Fixes #1847

See merge request !1345

Fix mysql migration

Fixes exception noted in https://gitlab.com/gitlab-org/gitlab-ce/issues/913

```
** Invoke db:migrate (first_time)
** Invoke environment (first_time)
** Execute environment
** Invoke db:load_config (first_time)
** Execute db:load_config
** Execute db:migrate
== 20141121161704 AddIdentityTable: migrating =================================
-- create_table(:identities)
   -> 0.1214s
-- add_index(:identities, :user_id)
   -> 0.1660s
-- execute("INSERT INTO identities (provider, extern_uid, user_id)\nSELECT provider, extern_uid, id FROM users\nWHERE provider IS NOT NULL\n")
   -> 0.0518s
-- remove_column(:users, :extern_uid)
rake aborted!
StandardError: An error has occurred, all later migrations canceled:

Mysql2::Error: Duplicate entry 'ldap' for key 'index_users_on_extern_uid_and_provider': ALTER TABLE `users` DROP `extern_uid`/home/git/gitlab/vendor/bundle/ruby/2.1.0/gems/activerecord-4.1.1/lib/active_record/connection_adapters/abstract_mysql_adapter.rb:301:in `query'
/home/git/gitlab/vendor/bundle/ruby/2.1.0/gems/activerecord-4.1.1/lib/active_record/connection_adapters/abstract_mysql_adapter.rb:301:in `block in execute'
```

See merge request !1344

Release announcement

@dzaporozhets wants a hashtag https://gitlab.slack.com/archives/general/p1419317692000272

See merge request !1340

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

Migrations separate

Sytse will tweet on merge.

See merge request !1343

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

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

Install guide

Add libkrb5-dev to upgrader /cc @dzaporozhets @valery

See merge request !1341

Mention the team

See merge request !1339

Rename sanitize in check task

This is to prevent the name clash between `sanitize_helper.rb` method sanitize and the method used to check if env variable is set in rake task.

See merge request !1336

Differentiate system notes

Remove unused has_gitlab_shell3? method

Use blob local instead of instance.

Disable / hide MR edit blob button if cannot edit.

Update gemnasium-gitlab-service to version 0.2.3

Fix dev user seed: ID was used twice.

Add tests for tree edit routes

Reduce the size of Docker image

Update the Omnibus package in Dockerfile

transfer error handler

[BUGFIX] Invalid branch in comparison

Fix Rake tasks doc README: add top level h1

Add theme type css class

Add link to OmniAuth config sample for Omnibus

Added a link to the OmniAuth config sample for Omnibus installations.

See merge request !1335