Adds support for ruby 1.8 in webhook example, issue #7763

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
Merge pull request #7798 from spuder/issue#7763

Adds support for ruby 1.8 in webhook example