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.

CONTRIBUTING typos.

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

remove rack attack middleware update

Hasn't changed since 7.2 release: https://github.com/gitlabhq/gitlabhq/commits/master/config/initializers/rack_attack.rb.example

Document the extra.sign_in_text setting for CE

See merge request !1027

Check for hooks directory symlink in gitlab:check

See merge request !1094

Dont rebase pushed commits

/cc @jacobvosmaer

See merge request !1095

Add dormant New Relic gem

See merge request !1089

The gem can be enabled and configured via environment variables.