Allow saving a config file

[nover]

The configuration file could include settings like:

• what .csproj to perform version bumps to
• which test-projects to run BEFORE performing the version bump (like npm version does it)
• A commit message template, like : "Creating release %v" and %v is replaced by bumped version

We could call it .version.json or similar.

Enable the CLI to search "upwards" for a config file, i.e we are in src/ when running but the config is stored in the root of the repo.

[ghost]

I would prefer convention over configuration. I do see the value of the "run tests before bumping", but I would suggest that it is done by having a script with a specific name. If that returns 0 then continue otherwise fail. I think this would provide the greatest freedom.

This could however be difficult to get working cross platform.