https://github.com/github-for-unity/Unity/pull/74

Moving logic to validate a new branch name to a testable location; Adding unit tests to check boundary conditions

Use OnEnable/OnDisable instead of OnShow/OnHide, it's more consistent with Unity's
naming and our own window class.

AuthenticationView was missing some calls from the window, fixicate.

- Make authentication window into a utility window (non-dockable).
- Force constant size.
- Shrink gap between label and
text field.
- Rename authentication window title to Authentication to match menu
item.
- Remove unused fields.
- Enable wordwrap for errors.
- Use title capitalization for labels.

Trying to load keychain; trying to handle scenario where item is in the cache but not in the credentialManager