update gitlab shell to 1.9.8 for gitlab 7.2.2

Typo it -> its.

formatting improvements to 6.0-to-7.3.md

As committed in https://github.com/gitlabhq/gitlabhq/commit/873acfd9aa54e801d5786c32b05c4f8ad21af72a GitLab 7.2.2 requires GitLab Shell 1.9.8. Fixes https://github.com/gitlabhq/gitlabhq/issues/7806.

Prevent default action when closing zen mode

Factor zen mode.

Adds support for ruby 1.8 in webhook example

By using the hash rocket syntax, the web hook will work on older versions of ruby (1.8) in addition to 1.9, 2.0 ect..
Moves do .. end to separate lines for ruby-lint.

Additional Information:
http://stackoverflow.com/questions/25899476/webrick-gives-error-unexpected-expecting-end
https://github.com/spuder/r10k_gitlab_webhook

Ignore tags file.

link to page that discusses how to generate ssh key

Improve zen mode internals.

Release branch earlier

Fixes #1603

See merge request !1102

Same version restore

Warn users about this.

See merge request !1101

CONTRIBUTING typos.

Add semaphore config

See merge request !1100

standardize capitalization

update rack_attack link to history page

Delete stray brace

* seems like a small mistake ;-)

check resque.yml.example for config changes

CI setup doc

I want do describe what CI services we use

See merge request !1099

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

Security in dvcs

Explain why access & sharing are the same.

See merge request !1097