When using Subvertpy as an SCM backend, adding an HTTPS repository

requiring Basic authentication would fail showing:

A repository was not found at the specified path.
Weirdly, when passing the `subvertpy.AUTH_PARAM_DEFAULT_*` constants to

`subvertpy.ra.Auth.auth.set_parameter()` instead of the corresponding

strings, it works.

Also, in `accept_ssl_certificate()` username/password were not passed.

Created Docker container form easybe/alpine-reviewboard:wip
Sucessfully added an SVN repository requiring HTTPS and Basic auth