feature: client-id hierarchy
feature: client-id hierarchy

this commit enables *kellner* to search for valid mapping files in a
set of folders: for an incoming request "/map" the following files
are checked:

    /client-ids/O=x,OU=y,CN=z/map
    /client-ids/O=x,OU=y/map
    /client-ids/O=x/map

this makes it easier to provide the same repository or feed a whole
organization.

thz/kellner,carosio/kellner