Add possibility to skip changelog for pre releases

[Deadvi5]

In order to avoid duplications in the changelog, it would be nice to have an options like --skip-changelog that allow to skip changelog writing with pre-releases.

To summarize with an example:

versionize --pre-release alpha
versionize --pre-release alpha
versionize --aggregate-pre-releases

Will actually produce

v1.0.0-alpha.0

• featA
  v1.0.0-alpha.1
• featB
  v1.0.0
• featA
• featB

Request scope is

versionize --pre-release alpha --skip-changelog
versionize --pre-release alpha --skip-changelog
versionize --aggregate-pre-releases

Will produce

v1.0.0

• featA
• featB

A more optimal alternatives is an option that delete alpha.0 and alpha.1 from the changelog when a stable is released. In this way we can see changelog of --pre-release until a stable is released.

The flow will be

versionize --pre-release alpha 
versionize --pre-release alpha

v1.0.0-alpha.0

• featA
  v1.0.0-alpha.1
• featB

versionize --aggregate-pre-releases --skip-prerelease-changelog

v1.0.0

• featA
• featB

[cabauman]

Hey, thanks for sharing the idea. We'll look into it.