Webhooks implementation

[lunny]

This is a summary issue for all the requirement related with webhooks

• Push, PR open/close/reopen/edited/assigned/unassigned/label updated/label cleared/synchronized, Branch/Tag created
• Webhooks for repo creation/deletion PR(Webhooks for repo creation/deletion #1663)
• Webhooks for issues Issue(Webhooks for issues #132) PR(Add more webhooks support and refactor webhook templates directory #3929 )
• Pull request webhook should support all PR-related events Issue(Pull request webhook should support all PR-related events #895)
• PUSH event hooks not sent for branch removal Issue(PUSH event hooks not sent for branch removal #2105)
• Webhook delivery test unavailable for organisations Issue(Webhook delivery test unavailable for organisations #2219)

[lcges]

@lunny How is progress on this task?

[lunny]

@qdbdbp I have updated the issue content. Did this answered your question?

[lcges]

ok.
Do you think all webhooks are coming in to release 1.3?

[lunny]

I wish that.

[daviian]

@lunny PUSH event hooks not sent for branch removal Issue #2105 is done

[lunny]

@daviian done.

[hellasteph]

Does this issue accept bounty? I would like to support for someone to complete this. ;)

[lunny]

@hellasteph This is a summary issue, so I think no one people will work on all these issues. It's not suitable for bounty I think.