Added 'GitVersion init' command which creates a sample GitVersionConfig....

...yaml file

Looks like this:

``` yaml
# assembly-versioning-scheme: MajorMinorPatchMetadata | MajorMinorPatch | MajorMinor | Major
# develop-branch-tag: alpha
# release-branch-tag: rc
# tag-prefix: '[vV|version-] # regex to match git tag prefix
# next-version: 1.0.0
```