Abstract away "providers"

[jamiebuilds]

So there are a lot of different systems for getting the information necessary for changelogs.

It would be nice if lerna-changelog could support a variety of different services and systems for generating changelogs by having some abstract form of providers that could be setup in repos.

[gigabo]

Good idea.

There are currently three key pieces of information for each changelog item:

• Category
• Description
• Author

Any of these could come from:

• Pull request
• Issue
• Commit
• ???

The info doesn't necessarily need to all come from the same source (e.g. description from issue, category from PR, author from commit).

[trevordmiller]

Would love to see Bitbucket support. We are currently manually creating changelogs.