Added Gitea, GitBucket, Bitbucket, Bitbucket Cloud and GitLab webhooks

[tvrzna]

References #12.

Added Gitea, GitBucket, Bitbucket, Bitbucket Cloud and GitLab webhooks support. This pull request does not contain update on README or Dashboard/Integration page.

Gitea

Developed and tested with self-hosted version 1.4.0

https://docs.gitea.io/en-us/webhooks/

GitBucket

Developed and tested with self-hosted version 4.23.0 Uses SHA-1 for signature.

https://github.com/gitbucket/gitbucket/wiki/API-WebHook (it says "The GitBucket api/webhook is designed for compatibility with GitHub's implementation.", but that is not fully true)

Bitbucket

Developed and tested with self-hosted version 5.10.0 Uses SHA-256 for signature.

https://confluence.atlassian.com/bitbucketserver/event-payload-938025882.html#Eventpayload-Push

Bitbucket Cloud

This one is only developed by documentation and sending custom REST requests. Does not support (by documentation) secret nor signatures.

https://confluence.atlassian.com/bitbucket/event-payloads-740262817.html#EventPayloads-Push

GitLab

Developed and tested with self-hosted version 10.7.1

https://docs.gitlab.com/ee/user/project/integrations/webhooks.html#push-events https://docs.gitlab.com/ee/user/project/integrations/webhooks.html#tag-events

[NiklasRosenstein]

Thanks a lot for your work, @tvrzna – TBH I didn't test any because I lack the time and capability to do so. If something doesn't work, someone will complain when they want to use it :')