Add helper commands to release major, minor and patch versions

[megawubs]

Right now we have to manually set the new version number. This is something that is not always on the top of mind and has to be searched. Instead I would like to see the following:

changelog:patch-release: Releases a new version where the patch version number is automatically upped by one

changelog:minor-release: Releases a new version where the minor version number is automatically upped by one

changelog:major-release Releases a new version where the major version number is automatically upped by one

Any thoughts on this?

[markwalet]

I agree, this methods should be implemented.

I think we should swap the naming of these commands:

• changelog:release-patch
• changelog:release-minor
• changelog:release-major

Some functional requirements that come to mind:

• The command should at least output the new version number, it can be appended with a list of changes that are moved to the new version.
• There should be a --generate (not sure about naming) to autogenerate the new changelog file. (Described in #15)
• The command should not create a new tag for git. This should be done manually.