Mask * don't allowed in slaves

[ebuster]

I spend many time to debug why anything is not working for me. After looking to sources I found a reason - masters processed by Regexp, but for slaves used simple string comparison.
Documentation does not says that mask is allowed for slaves, but intuitively I think that masters and slaves processes equally.

So, I can propose only two solutions:

1. Improve docs, and highlight that moment.
2. Update slaves processing to support regexp.