add slack notifications for wiki pages
## What does this MR do?
Lets the Slack service be configured to send notifications when wiki pages are created or edited.
## Are there points in the code the reviewer needs to double check?
I'm just starting to get familiar with the Gitlab codebase and I was unsure on how to get the wiki page url to pass it to the slack message, on whether or not I needed to refactor the create/update methods for wiki pages from the controller to a service (but seemed necessary to test it better), and if I needed to add a column to the web hooks table or if the services table would have been enough. Please let me know if I should change anything and I will improve the MR, thanks for checking :)
## Why was this MR needed?
Related to #563 and fixes#4233.
See merge request !2998
write_ was renamed to create_
modify_ was renamed to update_
So now in update action we have next code
def create
can?(current_user, :create_issue, @issue)
end
def update
can?(current_user, :update_issue, @issue)
end
Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>
Robert SpeicherandYorick Peterse
Rémy CoutableandYorick Peterse
Gabriel Mazetto
Robert Speicher
Guilherme Garnier
Stan Hu
Dmitriy Zaporozhets
Jeroen van Baarsen
Vinnie Okada
Loic Nageleisen
Marin Jankovski