Fixed setup of zypper repository name if no alias is specified

If no alias name is given in the kiwi <repository> section, kiwi
builds a name from the given source URI. If the source URI does
contain credentials information appended as token after the RFC
specified '?' sign the repo name contains this information too
which results in an invalid repository name for zypper. In order
to prevent this kiwi cuts off the information '\?.*' from the
URI and build the name from the remaining part