add rake tasks for web hooks management
add help page for web hooks management using rake tasks
Update logic for validates_merge_request for tree of MR

For case:

Merge request №1: branch "feature" to "release" and remove "feature" branch

Merge request №2: branch "release" to "master" and remove "release" branch

Merge request №1 - broken :(
Remove -y option when removing puby1.8

Since it is easily could break installations running on the server - hence the person doing the install should be able to make the decision to remove himself.
Add iid field to issues and MR
Sett iid on create. Use iid as value to_param
Create task to create iid for existing issues/mr
Find issues and Mr by iid in controller
Show iid as default id for issues, mr
Show iid in event feed and uatocomplete as default id for issues, mr
Iid improvemets

* call set_iid before validation
* make rake task pass event if objects are invalid
* show iid in comment event at dashboard
Remove the dependancy of grit from class Network::Graph
Better message for migrating global projects
Its time for 6.0.0rc1
add link on realisation api for java client
Added Gitlab::Access module
Refactor access roles methods
Fixing tests after adding iid for issues/mr
Searching for issue/mr by iid in markdown
Rename wiki repo if project repo was removed