HTTP Basic Authentication: Don't fail on colons (":") in passwords

[manubahr]

fitnesse.http.Request#getCredentials() fails to split the basic authentication header value correctly if the password contains one or more colons (":"). The splitting has to stop after the 1st colon separating user-id and password. Following colons are part of the password.

See:

• https://www.rfc-editor.org/rfc/rfc7617.html page 4

Furthermore, a user-id containing a colon character is invalid, as
the first colon in a user-pass string separates user-id and password
from one another; text after the first colon is part of the password.

• https://stackoverflow.com/a/28115727

[fhoeben]

@manubahr do you mind resolving the merge conflicts so we can merge directly?

Thanks for your contributions!