Support Atlassian Bitbucket server

[RuslanSafa]

Thanks for the cool plugin.
Use Atlassian Bitbucket v5.14.1
When searching for a plugin gives a link:
https://url/$PROJECT_REPO/$PROJECT/pull/149/files#diff-935d832518311fa4a605496e4a00cc33
But the real path:
https://url/projects/$PROJECT_REPO/repos/$PROJECT/pull-requests/149/overview

[shiraji]

At this moment, this plugin only supports bitbucket.org, not Atlassian Bitbucket server.

The URL format is https://bitbucket.org/shiraji/$PROJECT_REPO/pull-requests/1

Let me think how I can support Bitbucket server.

[shiraji]

@RuslanSafa

In order to support new hosting service, this plugin needs to know following information:

• default merge commit message
• default squash commit message (if any)
• PR url path format (= https://url/projects/$PROJECT_REPO/repos/$PROJECT/pull-requests/149/overview)
• commit page url format
• The name of the pull request (e.g. merge request in GitLab)
• the page of icon that I can use (if any)

Unfortunately, because I don't have any way to use the hosting service, I'm not able to debug or fix bugs if something happens in future.