More :lipstick: for the codebase

- [x] kill of a bunch of unnecessary namespaces in the test suite
- [x] added `Helper.Username` as a shorthand way to get the current login
- [x] 80 char word-wrap for the `README`
- [x] `Helper.DeleteRepo` should wait for up to 15 seconds to ensure proper tidy-up
- [x] added  `ctor` overloads to `NewCommit` so that you can create an orphaned commit (no parent) or simple commit (one parent)