Please incorporate enforced HTTP Basic Authentication (when configured so) (Issue #222)

This feature enforces HTTP Basic Authentication when the following properties are set:
* `web.authenticateViewPages` equals true (default assumed `false`), and
* `web.enforceHttpBasicAuthentication` is set to be true (default assumed to be `false`)

This is achieved by prepending the `EnforceAuthenticationFilter` and configuring it accordingly.

When logging out, the credentials set in Basic Authentication will be remembered by the browser; therefore, a logout page is shown requesting to close the browser if that was the authentication method. This page has been localized for EN, NL, and ES.

**TODO**:
- [ ] translate `GitBlitWebApp_ja.properties`
- [ ] translate `GitBlitWebApp_ko.properties`
- [ ] translate `GitBlitWebApp_pl.properties`
- [ ] translate `GitBlitWebApp_pt_BR.properties`
- [ ] translate `GitBlitWebApp_zh_CN.properties`